Inefficient Market Theory for the HP collector


HP-15C, new, with book, case, and manual, $50 + shipping, required superglue on two heat stakes, rubber cement to replace feet,
and is now perfect. Thanks FixThatCalc for the advice!

HP-42S, C rev, good used condition, with case, no manual, $75 + shipping,
required alcohol cleaning of keys and superglue under bezel, now works well.

HP-48GX, good used condition, R rev blue display,
with books, case and cable, $50 + gas

HP-19BII, good used condition, no manual, good side battery door, $20 + shipping, required rubber cement on one foot.

HP-12C, 2002 model, with manual, $10 + shipping, en route.

Do you want deals like this? Read on. I have most of the LCD models I want, and
LED models are not showing up, so I might as well write this up now.

An efficient market is one in which (A) buyers can easily find sellers and (B) transaction
prices are visible to all participants. Ebay is an efficient market.

An inefficient market is one where either A, B, or both are false. Garage sales are
inefficient markets.

In efficient markets, collectors' items like HP calculators are expensive. The market
quickly establishes a price range for each item, and it is hard to beat the market price.
Anyone trying to buy a 15C or 42S on Ebay knows what I am talking about.

In inefficient markets, collectors' items can sell cheaply compared to the efficient
market price, but you have to waste a lot of energy to find them. I got a good 11C for $25
and a fixable 41CV for $5 at thrift stores, but those were lucky finds.

What the buyer really needs is a market that is inefficient for most people, but efficient
for him. There is such a market on the Internet: craigslist. Craigslist is stubbornly
local. It provides no global search (A is false.) There is also no "completed items"
search (B is false.)

However, there are third-party global searches for Craigslist which allow you to search
all the sites, and you can use Ebay to check "market" prices. A and B are now true for you.
I got all the deals above using this URL:

Search for "hp calculator" and "hewlett calculator". Sometimes the search fails partway
through, but most of the time it works. You will see some calculators selling for
Ebay prices, and some people posting want-ads for calculators. However, there are
also some very good garage-sale prices. The search for "hewlett calculator" is
particularly good, because people who don't put "HP" in the title get fewer buyers.

When you find a good deal, just email the seller and ask him to ship it. Most sellers
are willing to ship calculators, and Priority Mail costs under $5 for a calculator
without manual.

Many users do not have Paypal. I have sent cash through the mail about 8 times now, and
have not been burned yet. I have rejected two calculators which were in poor condition,
and in both cases I got my money back. One seller offered a 200LX for $30, and while the
money was en route, looked online and realized his mistake. He sent me my cash back
plus $5 by way of apology!

These sellers are ordinary folk who value their good karma. Your mileage may vary, but
I have had good luck. On the other hand, I had a scammer in China respond to an ad
that I posted on hpmuseum.

Now I just need a source for a good HP-97.



Good to know there is a search engine for Craigslist. But like you I have not had luck finding the LED models. I have had better luck on the Museum boards, and on eBay.

Regarding the 97, they can be had untested, or with known problems, on eBay for $100-$125. Unless you buy one refurbished, expect to repair both the card reader gummy wheel, and any number of problems with the printer. A refurbished 97 will run $350-$400 typically, more with accessories.


I've noticed a similar thing when shopping for a computer. Craigslist has both outrageously high prices (people want the same price they paid 3 years ago for their computer) and a few low prices. A *lot* more variance in the prices. eBay prices to seem to converge after a while at a price that is not much less than what you could get the item for new.

I've not had any luck finding old HP calculators on craigslist though...


Here's one: HP-11C for $25. I'd buy it except I have one already.


Shhhh, Mike, you're giving away all our best tricks! ;-)

But this does work. Today I picked up two calculators:

1. HP-48GX rev. R in almost perfect condition, including original shrink-wrapped manuals and box

2. HP-32SII in very good used condition, also including original shrink-wrapped manual and box (what is it with people who don't read the manual?!)

I got both for $100 plus gas and the hassle of getting up at 7:30 on a Saturday morning thanks to Craigslist. So they're definitely out there, you just have to be vigilant to get them. And this is my first ever 32SII, so I'm a happy camper.

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