This is a
link to a 5 year old article that is still pretty relevant from KIP.
The US healthcare system has undergone many changes since then, but overseas less so. One of the links in the article is to
Patients Beyond Borders which may be helpful.
So far as anecdotal experience, I know several folks who will only get dental work done in Mexico, I chose Canada for my own eye surgery 15 years ago, and my best dentist ever worked in CA but was trained in and transplanted from the Bahamas, no cost savings but far superior work.
I am thinking very seriously of abandoning the American "Medical Industry" (no healthcare involved) in the next year or two for myself and will likely opt to do an annual health tune-up and testing rounds trip out of country. I will use the findings to choose what kind of insurance to buy each year. I am very much afraid that the data from routine checks will be used against US citizens in the near future and the advantage of outsourcing would also be privacy until/if I wish to disclose.
For both cost and quality I have transferred most of my mothers care to private providers here in the states (it's cheaper and better!).
ETA: Don't forget currency exchange rates, it can really add to the savings when the dollar is strong like it is now.