How can I approach a dentist to get my teeth taken care of without a lot of money or insurance?

I have been to a few dentists in the area I live in in the past 20 years & the gouge people. I now have front teeth that have black marks in between the teeth. I really want to get them taken care of. I thought about just visiting each dentist after calling & asking if they would just fix 2 teeth in the front. I was wondering it they would barter but I am not sure about how to do that. I can babysit, clean house, organize, make calls to confirm appointments.