Anyone looking to sell music from an indie game should follow Artem Bank's example with the soundtrack from Star Ruler (though maybe charging a set fee instead of a pay-what-you-want scheme). Offer up the soundtrack from a website in whatever format the buyer wants (mp3, FLAC, etc), and don't tie it down to iTunes or some service like that. I know I still chipped in a few dollars directly to Mr. Bank despite having bought four copies of Star Ruler to this day.