This isn't really the kind of thing you can get at Wal Mart. Or any music shop for that matter. The price definitely is worth it if you're a fan of Miles Davis and chiptunes.
From my understanding, I don't know if the music is done, however, the album will be coming out early August, and if you do the $5 donation, you get an early download of it before it becomes a free release. $30 gets you the physical disc.