Based on what you said above, perhaps I can help at http://www.goatstore.com
And, correct me if I'm wrong, but everyone suggesting eBay, he's looking for a few cheap games for a bunch of systems. VERY rarely will you find an eBay auction containing five of each NES, SNES, N64, Genesis, 2600, Saturn, Master System, Odyssey 2, Intellivision, and so on games all in one package. eBay works if you're looking to start a, say, 2600 collection and you just want a system with 100 games, but if he is looking for lots of stuff, then that won't work out right.