Get a Wii, then you can download the old skool Nintendo games (aswell as Sonic, et al) for a few quid each.
A few quid each? You actually pay for them?
Get a memory card, install Homebrew channel, download some emulators, download some roms and you're done - all the old skool games you'd ever want (Nintendo, Arcade, Sega etc) for under £20.