I think you might be better off finding a good dentist and bartering a discount for paying cash when the work is done. If it is a crown, you can do 50% on the first appointment and 50% when the crown is seated - or something similar.
You may find a dentist willing to trade services, but they would be exposing their real-world identity since you would have to go to their office for whatever is being done. It is hard to imagine a good dentist willing to take that risk - they have too much to lose.
You can get an individual dental insurance plan here -
www.ehealthinsurance.com - possibly for less than you would expect.
Whatever you do, get a good dentist. Sometimes bad dental work doesn't become apparent for several years - and can get expensive to fix. Also, there are some flakes that will try to get you to have work done that you don't need.
If you need a root canal, go to an endodontist. You may need a referral from a dentist for that.