HI, I hear that Dr Lagos in Mexico appears to be a safer bet. I would be VERY careful otherwise. Simply because the cost is cheaper does not mean it is worth risking. Some people I know who went there to a particular dentist have had to go back for repeat visits in an attempt to fix the job that was not done properly, this meant ongoing costs, travel and ending up with dental problems, often that they have had to go to other dentists to try and remedy.
So though the intial cost is very attractive, the risk attached to it and possible long term expense because of it, may not worth it. Please make sure you ask around as you are doing already.
Here is a link to an Amalgam Forum you could ask on and read the posts. Click below.