so i just recommended this site HALF.COM to kidson2004 for those people in the US.
i get most of my games from here.
the site is an EBAY affiliate, and can be described as ebay without the bidding and only individual items and no lots.
for example on the prices for things on the site, here is a Resistance 3 Half.com-to-Gamestop comparison:
Half.com: Resistance 3 (Sony Playstation 3, 2011): Video Games
Resistance 3 for PlayStation 3 | GameStop