http://www.cheapassgamer.com/
http://cheapcollegegamers.com/
http://slickdeals.net/
Ballin' on a budget.
Cheap Ass Gamer usually finds good deals first, and many websites credit them for the findings.
Cheap College Gamers is pretty good.
Slickdeals is the best overall, always keep an eye on that website. I have it as my homepage. Oh and there is Newegg, and Woot, but they are not gaming related.