I am starting an internet "radio station" that will NOT broadcast
music, but rather stream it based on user preferences (like
Launch.com). The station will feature unsigned independent bands only.
If I find their music on my own and play it without consulting them,
do I have to pay them a royalty even though they are not a member of
ASCAP, BMI, or any record label? Am I even allowed to play their songs
without their permission, providing I give them due credit?

You see, I'm trying to get this station off its feet, so it would be
very nice if I could browse sites like SoundClick and PureVolume to
find artists that my listeners would appreciate. Relying on band
submissions won't cut it. If I cannot find and play music on my own,
do you have any recommendations on building my song inventory?

Thank you very much for your help.