Bandcamp really is fantastic and will always have a special place for me. Just let me buy the stuff, choose my format, (even ogg!). Even let me sample it a good amount of times, and no obnoxious nonsense on their website. I hope they're doing really well.

That said, for a larger number of really major artists, I heard about something called HDTracks. I haven't tried them yet, but it seems that they sell FLAC in 24 bit audio.