Some 40+ years ago I purchased (with my companies money!) a Hewlett Packard calculator with more functions -?

HP-15C calculators sell on eBay for more than their original purchase price, so you are not alone in your love of old HP calculators. However, if you really want to talk religion, let's compare slipstick collections. :-) About the same time you were buying your HP, office supply stores and the like were remaindering all of their slide rules. I snapped up a 10" mahogany K&E for $0.25 U.S. once (same model that my dad used at MIT) and still pine for the "Dietzgen that got away."