HMV (or at least my local one) has two large bins full of old cheap cds... you can pick em up usually under CDN$5. There are also a couple of racks of heavily discounted singles and albums; usually a bit older as well. I've always bought a ton of CDs (I'm at over 600) and now DVDs, so I can say the situation is not nearly as bad as everyone who never sets foot in a music store makes it out to be. The things could be a bit cheaper overall though.
Stores not specializing in music will often have very cheap cds just to get people into the stores... so be sure to dodge those pesky sales people!
