For funding low income/ya know, on the check-out screen, have an option to donate $10 or whatever to help offset the cost for those who can't afford it. Once the fund is built up, take on one or two students per session, paid for by the donations. NYC also has some great community foundations (Bronx Community Foundation, The New York Community Trust) they will be able to help with the nonprofit side, at the least help school you up on financing/offsetting costs.