Stay out of Tijuana as the dentists there are the most expensive in the border area.
Nuevo Progresso,Near Brownsville texas has dozens and dozens of dentists who want your business. Most still use mercury but will put in Mexican gold for you.
Price for gold fillings,onlays and inlays, were in 2004 about 120US dollars. Crowns maybe 150. Gold is Up,business is way down due to border issues.