While I don't specialize in band management or promotion, I have some second-hand advice as my boyfriend is a signed musician to a major label. From my understanding of your question, it sounds like they have some sort of following already - from here, I'd identify within the US or Europe where...
Retention - if you build something people want/use AND come back and use often, then you can usually figure out a business model to make it work (if there's a big enough market).
We've done something similar, but by delivering pizzas. You can get them talking about you before you come in if you have it delivered, wrapped in gift paper, with a mysterious, clever, anonymous note complementing their pipes. Then drop in and ask if they liked the poster. It will probably go...