Thanks to Laurent I found Jamendo, a distributor of Creative-Commons-licensed music, and from there Magnatune, with similar goals. Magnatune artists get 50% of proceeds from sales of their work. Here's a Bach cantata from Magnatune:
The quality of the music is good, but there's an annoying voice between each track that tells you the album and artist name, which you knew already. I hope the paid version excludes this.
I'm going to explore these sites some more. It might be time to bid farewell to the iTunes Store, and all those Big Record Labels and their fascist anti-piracy methods with it.