I used to buy from DiscountCD.com (and DiscountDVD.com) for their no S&H costs. But lately I've been looking for things on eBay and Amazon. The greatest success I get is to find it on Amazon, then click on the Used link. Hundreds of small shops are selling through this method, and I've had good sucess in chopping off a few bucks. So far, the sellers have all been prompt and reputable.

I also have to admit that I abuse CMH and BMG every year or two to stock up with a dozen or so freebies by rejoining. Fullfilling the BMG obligation is easy, but I'm staring at the need to buy 4 more at CMH in a year or so...