I'm guilty of buying a houseload of crap from Amazon (though I just paid $7 extra for the privilege of using someone else).
Amazon is playing the pricing game, which is a race to the bottom. And, as Seth Godin says often, "The problem with a race to the bottom is that you might win. Or, even worse, you might come in second."
In the meantime, I try to make Black Friday and Cyber Monday "no shopping days"