Millions of Americans and Canadians travel outside their countries every year for medical work.
Aside from Mexico and Costa Rica, India is also a hotbed for that kind of thing. Often you are talking about USA trained doctors setting up practices to specifically cater to foreigners.
This article is a bit dated now but shows where the trend was and is going - medical care is global instead of local.
http://articles.latimes.com/2008/nov...ness/fi-cover2
Cowperson