A while back I listed a few things you'd never get on iTunes, including bargain basement albums. Their fixed single pricing fixes songs to a low point, but also means they won't go lower. Albums are around $12 on iTunes, a price a little to close to the real world CD price to be attractive. At least to me.

Amazon MP3 on the other hand has variable pricing. This means most of their tracks are between US89c and US99c but that some longer tracks cost more.

It also means they have heavy album sales (from rollingstone)...

Amazon MP3's "Daily Deals" offers popular titles at a hefty discount, while "Friday Five" unloads five classic albums for $5 weekly from Friday to Sunday. In honor of Coldplay's recent release, "Daily Deals" offered X&Y for $1.99 on Tuesday, A Rush of Blood to the Head on Wednesday for $1.99, Parachutes on Thursday for $1.99 and Brothers & Sisters on Friday for 99 cents. Similarly, Madonna’s Hard Candy, which is still going for $13.99 on iTunes, was recently a "Daily Deal" at $3.99. The "Friday Five" selections are equally tempting: This week, The Rolling Stones' Let It Bleed can be had for a single Lincoln, and you don't have to worry about ripping it to your iPod, because it's already in DRM-free, digital form.

In the comments a lot of people have said that between $2 and $5 is the maximum anyone should be expected to pay for MP3s of a CD album, particularly as you're not actually buying anything.