Think Geek is selling (it has units on back order) a unit called the Pocket Retro Game Emulator for $99. It looks pretty cool weighing in at about the size and form factor of a Gameboy Micro. It is also the most reasonably priced handheld emulator I have seen that appears to handle systems as modern as SNES and Neo-Geo nearly perfectly. Unlike some other systems that require lots of tinkering/hacking with questionable results the Pocket Retro Game Emulator has built in emulators for a handful of classic systems. As anyone who has picked up a GP2X can attest hacking becomes tiresome.
Think Geek offers Free UPS Ground shipping for all orders over $75 if you enter the code SHINY during checkout.
Get yours at http://www.thinkgeek.com/electronics/retro-gaming/bd6f/
or it appears to be available as the Dingoo A-320 at Deal Extreme http://www.dealextreme.com/details.dx/sku.23032