Calculators you regret not buying?

[JimP]

Two answers. One, I was given a TI-58 for my 18th birthday and it served me very well for the rest of college and through graduate school. If I could have a do-over I'd have waited for a TI-58C. (The 59 was more than my family could have afforded and there's no way I'd have asked for one!)

In the HP world, which I entered when my TI-58 started to develop a few problems (not insurmountable though) when I was in graduate school, I wanted a 42S but couldn't afford it -- had to wait until I had a real job. Bought a Casio FX-4000P which lasted me a few years until I loaned it to a friend who needed a calculator. He didn't break it, but in the interim I became an HP aficionado and started out with a 48G (again, didn't feel as though I could spring for a 48GX). Over the years accumulated several others, a 33S, then a 49G (when the 48G started developing input problems), then a 35S, a 50G, and a Prime, along with a 27S for grins, and a 17BII+. Finally a 20b (died) and a couple of 30bs, one of which I converted to a WP34S, but both of these have developed some keyboard problems. These days I usually stick to the Prime and the 35s, but the 15C CE remains in my drawer for now as a collectible, along with a couple of mint unopened 40GSs and a 39GIIs.

Various calculators, some from other manufacturers as well, dotted around the house because you never know where and when you might need one, and they're SO much more satisfying to use than a smartphone application.

But I do wish I had an HP-67...