A few days ago, at a consignment shop, I found this little gem:

It's the more expensive, metal version. I gather it's the very first really handheld calculator.

It's working perfectly, and it's in good physical shape.

It took some time to understand that addition and subtraction work in RPN mode, while multiplication and division work in Algebraic! :)

Anyway, now I'm wondering how much could it be worth. I did some searches on eBay but could find none there. How rare is it, really? How much do you think a collector would pay for it?

Thanks,

Cristian