(I still have my RPN HP-35 from when they first came out. Also have an HP-97, card-programmable. I really, really liked those two.)

 

I never got into the RPN thing, but I do have a brace of high-end TI calculators from the '70s and '80s, including the very cool magnetic-card-programmable TI-59 that cost (IIRC) about $300 (in 1980s dollars!) I never could afford the thermal printer for it, though.

The odd thing is that now I actually prefer my older TI-82 to the whiz-bang TI-89. Those extra bells and whistles make it harder for me to use!