I'm currently working on an app which would help musicians collaborate schedule with each other easier then via email/phone etc.. Also for groups like Bands, Choirs etc.. But I'm having a hard time finding the right research about how many serious musicians are out there doing it for a living, Where would you look as a start? I've tried searching for "band forums" "musician forums" etc.. But that doesn't help much
I would suggest spending some money and cash hanging out at bars where some of these bands perform, Also, try to find a way backstage to talk to the musicians after they perform to do your research. If you're going after well-off musicians, contact their agents or band managers. They are always looking to make or save more money.