regarding who'll pay for mp3s if they are available:
itunes music store
nufonix.com
beatport.com
audiolunchbox.com
trax2burn.com
warprecords.com/bleep
epitonic.com
foryourears.com (eventually)
i buy mp3s. i buy vinyl. actually, now i buy more music than ever before b/c the mp3s i buy are 99% other genres, stuff i don't play as much, stuff i was always curious about but didn't want to start buying in vinyl, etc etc.. so actually the existence of pay-for-download mp3s has greatly expanded my overall playlist(s).
all that being said, the single greatest thing about FS (imo) is still the one that gets talked about the least: customization. personalization. immediacy. zahn can make his Lost Boys track one afternoon and play it out that night. maybe never play it out again, make that gig that much more unique for the people who were lucky enough to be there. let's say you're a producer: what better way to test a track in a club environment that to actually *play* it in the club. no waiting, no goddamn acetates. try out x-number of different versions, eq settings, mastering passes before you actually commit the track to being done. or maybe do the exact same thing but with your mate's track... your mate who happens to live on the other side of the planet. and you play the track he made that afternoon. really dig that new ____ track you bought? ...except the vocal or the break or the bassline or the whatever? edit your own version, play that one. how many of us went nutty over the custom edits in those 2 surgeon sets from last september? and so on.