Counter-question:
Coursera is free only because it is financed and logistically supported by adequate infrastructure; the courses are fantastic and they are free; yet the tutors there do not have to worry about paying the bills. This is, in my opinion, the only sustainable model; sustainable in the long run, that is.
Why broke? If, in order to pay the bills, you need to spend 40 hours a week teaching and roughly another 40 hours preparing or doing follow-ups on these lessons, 10 hours on professional development plus spending some time away from your computer, how much time is left for doing pro-bono work? Realistically?