In my town there are a few places that offer private on demand CPR classes for those who need it and need it now. I think they charge $100 instead of the usual $60 for group class. Ebay is a pretty good place to find some of the equipment you need for a reasonable price. Craigslist would be a place to start looking for students. It all depends on how much you want to monetize your certification and how much time you have. This was something I was considering but with my other business and my "real" job as a nurse there wasn't much need.
PM if you want I'll give you all my ideas on the subject