I'd say check a couple of these out
http://www.google.ca/search?hl=en&q=bes ... dale&meta=
EB/Gamestop is OK for some older stuff, usually a few dollars more than the indies. But their newer used stuff is usually only $5 cheaper than new, which is pathetic (even more so considering there's enough people who buy them to keep them at that price).
Kijiji is a good place usually, too. Often people will try to get slightly more for them than what they'd get in a store (since most have checked), which means you can get it for about 20-35% off new price, no taxes. Then you get the crazies who think they can get Ebay prices...yeah, OK. But you can always place a Wanted add on Kijiji.