why are old HP collectibles?


Hi, you could say that I'm a reseller apprentice and I've noticed that vintage HP calculators are hot collectibles. You can pick one up locally for a few bucks, and online they'll go for a lot more. But it remains a mystery to me why does this happen? I mean, why in the world are old HP calculators so interesting? it's not obvious to me and I'd like to know why people collect this stuff? Is it an interest in old technology, is there any particular trait that made them so special? Are these real museum pieces...? Thanks,


Why in the world are old stamps valuable (plain sheet of paper)? Why is xyz valuable? Simple answer: some people see a value in them. As for HP calcs, this might be a) an item they couldn't afford when being a student or b) a fascinating piece of technological history or c) a daily-use item with a superb build quality not found on todays calculators or d) something the play around with (mainly 41). There certainly are a couple more reasons.
If you are simply buying them to resell them, you might as well move on - I would expect the forum to not-welcome you. If you are really interested in the calculators and not your profit, the forum will likely be able to answer all your questions.

Edited: 20 Aug 2008, 7:43 a.m.


I also think HP calculators are a breed apart because they redefined the engineering profession. When the HP-35 was introduced, our work changed -- forever. The slide rule will not return! This is a textbook case of a revolution brought by the right mix of imagination, innovation and technology. These are also the words which described HP engineering in its best time.

This is confirmed by the difference between today's market prices of scientific vs. financial models. The average selling price of an HP-11C is 4 times that of an HP-12C. It's an engineer's thing!

Joel Setton


In response to the comparison of HP11C price to HP12C in today's market (2008) the main reason the HP11C costs so much more then the HP12C is that the HP12C is still available at the retail level. If the HP12C was not available any more then I would expect the demand for used units to be quite high. The reason the price of the HP11C is so high is not as much demand as supply. I would think that if HP were to reissue the HP11C, at first the demand would be high, but it would trail off and sales would drop below the current HP12C level.


I'd like to offer a little different perspective.... (I am an HP-41 enthusiast and collector)

HP resellers perform a service. I wish there were more of them. The more people (with more time on their hands than I have) that are scouring garage sales, estate sales, and second hand stores looking for HP calculators, the more opportunities we will have to pick up things we might be looking for; and, supply being greater, the more reasonable we should be able to buy them.

That said, there are many unprincipled people reselling HP things that are out to make a buck, regardless of how they do it. To everyone trying to resell HP items, I offer these guidelines.

Take some time to carefully examine the item. Put everything you see, or know about that particular item, into the description. It is the seller's responsibility to do this. If you feel compelled to leave something out, that can ONLY be a bad thing. The buyer cannot examine the item themselves. Internet trade only works if the seller accepts this responsiblity. And before you use terms like 'mint', or 'excellent'; grab your dictionary and make certain you know what those terms mean.



Greetings Dan!
How is your ZVC project going!?! I have an observation about this comment:

...supply being greater, the more reasonable we should be able to buy them...

The Law of "Supply and Demand" is not so simple in real life as to be inversely related like they teach in High School Economics. There is an Elasticity of demand with respect to many popular HP models. I trust HP marketing staff knows this because this elasticity factors into their sales price for new models.


Howdy Allen!

With everyone's help, I have completed the parts manifest for the ZVC clone; and then went on vacation! :-)

I am back now, and when things settle down, I am going to place an order for a few complete sets of parts, and breadboard the circuit to test it before committing it to PCB.

Yes, sometimes we wish the principle of supply and demand (calling it a law is probably describing it beyond its characteristics) were straightforward and simple. I do remember from my college Economics courses that even if there is high demand elasticity, in theory anyway, price is always influenced down by increased supply. The Supply/Demand versus price slope may not be constant, but it rarely has any minima/maxima points and rarely goes totally flat. And I'd much rather have 50 HP-41CXs to choose from on ebay at any one time, versus 5. I think that would be good for all of us.


I recently finished an elasticity study on the HP41cv. I sold 108 new models, identically listed, identical in quality. I can post/email findings if you like.



Wow, where in the world did you get over 100 new HP-41CVs? What a find!

Did you sell them all at once, or one by one (to constrain supply)? If you constrained supply, it would obviously have been to get the highest price. That would demonstrate what I was suggesting, that the higher the supply, the lower the price. Correct?



No, I held the price relatively constant, and measured the elasticity of demand at various price points around the HP41CV release price of $325 given 'ample supply'. I do not doubt they would have eventually sold if the price was much higher or much lower, but it would not have yielded as much (or as interesting) data. By measuring the rate of sale (in days) at various price points during an 8 month period, I built a histogram. In brief, the rate of sale doubled by comparison when buyers were offered a price 10% below the $325 break point price (the release price of the HP41CV).

There were other factors that the data collected could not account for such as seasonal buying habits, foreign currency exchange rates (e.g. weaker US dollar in early 2008), effect of shipping costs on purchase decision, number of identical items listed at one time, competing or replacement items offered during the same period, effect of seller's availability to respond immediately to questions, times between successful ended listings and re-listing of similar item, etc... but I expect based on the data that these factors are a relatively small influence compared to list price.

Number	108
MIN 279.29
Average 306.51
MAX 361.45
Standard Deviation 20.43

I expect similar elasticity of demand curves (though not necessarily around the release price!) for other popular HP models: 15c, 42s, 48gx, should similar lots of NOS be found at some point in the future. It is unlikely. There is an old axiom that I believe predates the 'inverse law' of supply and demand. I read it in a college economics text book recently: "Without supply there is no demand".


Interesting data.

There is no "days to sell" data for the first and last group of data points. The last group is the highest offering prices, so that might mean that sales never occured at those prices? But at the other end, those prices were the lowest, I would assume sales took place. I am a bit surprised that at listing prices of about $260 and up, that every single one of over 100 units sold in 3.5 days or less.



the days to sell is a moving average. (Hence the lack of trailing and leading data). It smooths the function and corrects for multiple orders per day. (The average is better because the times I have are dates when recorded, not actual purchase dates.)
Cheers, al


Old HP calculators are valuable because they are generally very reliable, well designed, powerful, and have a logic system (RPN) that has a die-hard following.

Although HP still makes calculators that have RPN, their current offerings are closer to cheap disposable consumer electonics with questionable reliability and design that are a far cry from what they used to produce.

I couldn't imagine doing my job (structural engineer) without a good HP at my hands. Therefore, if I had to I would probably spend a lot of money on ebay for one.


The reason many of us are still using (and abusing) the 41 is: because the best is just barely good enough. We still build things with them with them. Part of the reason for the high price of the 11, 15, 41, 42, & 48 series is that we get payed well to do the things we do with them. RPN brings my IQ up to average.


My take on this: many of us who like these old HP's are engineers. For my generation (I am about 50), the HP-35 was something of a miracle, but not a miracle we could afford as students. My first HP was a model 29C. Although cheap 4-function calculators were available by then, you could not purchase something of the 29C's quality at the local department store. College bookstores and technical specialty bookstores kept them available in glass cases, and the cost was around $500 in today's dollars, by my recollection.

To own something like this, you saved up and sacrificed. When you received it, you really took care of it. It was like a very high-quality tool for a particular sort of craftsman. It was built to be very reliable, because HP could charge enough to make it so. Buying a new one was an event.

Today, you can buy a calculator with all that capability and more for a few dollars at a local pharmacy. However, you cannot buy a calculator that has the same level of build quality for any price. I can't honestly say that I would pay $500 for such a thing today, in light of the cheap substitutes and the way that computers have taken over so many computational tasks. However, I wish there were tools today that I felt the same enjoyment in owning and using as I did that 29C back in 1978. If you have not had that same experience, then collecting these things probably makes about as much sense as a pincushion collection.



I suggest that the scarcity of good calculators was driven by HP ceasing development/production of RPN machines. There was no decent alternative available, hence those available became more valuable. It seemed to be a crime to me for them lose their following, allowing others to occupy the field. Bean counters can't see beyond the next quarter. They can destroy even the best company. Sam


To own something like this, you saved up and sacrificed. When you received it, you really took care of it. It was like a very high-quality tool for a particular sort of craftsman. It was built to be very reliable, because HP could charge enough to make it so. Buying a new one was an event.


You've got the right! I scrimped and saved for two years to buy my HP-25 in 1977. I still remember how special that day was. I still have that HP-25 (along with other HP calculators) and it still works great.


It still works as good as the day I bought it


Thank you Don, you brought it to the point! Bought my first HP (25C) in 1977, too - the cutest tech toy I ever had :) But hard to explain to the young folks how proud I was of 49 programming steps and continuous memory - though no built in L.R., matrix nor integrate...

Continue enjoying :)


Bottom line: psychology.

People like to have things that pleased them in years past. Why do men pay big bucks for baseball cards they played with as little boys? This only starts the ball rolling, then the "collecting" thing can move/evolve on it's own due to other factors. People may hear that XWZ is now collectible, so they jump on the bandwagon, etc.

My dad once told me that to make money in collectibles look at what is truly valuable/innovative and is moderately popular. Then buy a ton of it and pack it away for 30 years. When the time is up, you will find people want to buy it. Your market is now older, has more disposable income, and already has fond feelings for what you want to sell as they tend to reflect more on the past.


Possibly Related Threads...
Thread Author Replies Views Last Post
  Value of HP "collectibles" heading south? Katie Wasserman 28 4,213 09-09-2006, 11:52 AM
Last Post: Katie Wasserman
  Value of HP collectibles Giancarlo (Italy) 14 2,565 07-18-2006, 09:51 AM
Last Post: Maximilian Hohmann

Forum Jump: