if you want to go to Mexico, Dr Francisco Sauceda in Monterrey and Dr. Laura Carmina Cardenas in Tijuana are very well-known in bariatric circles. They've worked on A LOT of bariatric patients and specialize in massive weight loss patients.
Dr. Joseph Capella in New Jersey has also operated on a lot of us (and specializes in massive weight loss patients, too), and his prices seem reasonable compared to a lot of other US surgeons (haven't seen anything recent on him, though)
several people here have gone to Miami for plastic surgery because supposedly it's one of the cheapest areas in the country for that - I don't know any names, but a few people on here have gone there and can probably give you some recommendations. The prices they've gotten don't seem much more than the prices in Mexico
oh - Dr. Joseph Michaels in Rockville, MD has also been used by a lot of bariatric patients
I personally would look for someone who specializes in body contouring for massive weight loss patients or at least has done a BOATLOAD of them, because it supposedly is a complicated sub-specialty.