I think people already cross-shop dentists. When I had a root canal done I inquired at two places. And I'm not even very sensitive to it since I have dental insurance.
I would be nervous to do that. I trust my dentist, I know he does a good job, and is sensitive to my comfort, that's why I go there. I've been to a few terrible dentists before, and I've had to get dental work redone because it didn't last. Dentists seem to be so hit and miss. Doctors can be the same way, price isn't the only consideration.