That novelty band, Presidents of the United States of America, already has a streaming music app: http://arstechnica.com/apple/news/2009/02/bands-bypass-itunes-by-streaming-music-through-iphone-apps.ars
The Presidents of the United States of America isn't a novelty band.
Most fans don't care about where their money goes; have no inclination to design artwork for you; and might be a little confused about why your app wants their credit card number.
Most fans. Nine Inch Nails fans are not most fans.
You scratch my tape, and I'll scratch yours.