I've sold about half of my handhelds because I got tired of buying a ton of batteries and back in the day Ni-CAD rechargables sucked - basically lasting about 30 minutes in the Express and an hour in the Lynx.

Plus the Express screen was pretty small and was hard on the eyes for most games with tiny projectiles...
I've had:
Lynx, Turbo Express (GT), and a GBA - original "can't see shit" version - at least I got it free from a girlfriend way back
I currently own:
GB - peasoup, GBASP (traded in the free GBA hehe), and a DS-L
I always wanted to get a PC Engine LT but those are ridiculously expensive. Even now, the cheapest I've seen one in working condition was $700... For those that don't know, it's essentially a PC Engine tiny laptop.
http://www.ravengames.co.uk/engine4.htm To have one would be pretty sweet though~
