Try going to a local university's dental school.. they perform work there at half the rate of what private dentists will charge.

The work will more than likely be done by a grad student, but under the supervision of a licensed dentist/professor. It's just as good as going to a regular practice, but a lot cheaper.

But get that tooth taken care of ASAP. I waited too long to get a cavity filled on my back molar and got an infection.. but it's all good and taken care of now.