Emusic!
http://www.emusic.com/
If you're looking for some obscure/indie type music they are the place to check. Before you even buy anything they give you 25 downloads for free. They way they charge is by month. You have to buy a plan that's 40, 60, or 90 dl per month. It works out to about $0.20 - 0.25 per song.
Even if you're not interested in signing up for the service, the 25 free down loads is a sweet deal.