Why is there such a cost variance?

It is difficult to conceive the quoted cost in Puerto Rico considering the cost of the balloon. You must be very careful in selecting the procedure solely based on cost. The procedure is cheaper compared to surgical alternatives. No word yet on insurance coverage

Hi, 
The cost does very widely by location, and practice, though typically falls within the $6500 to $8000 range in the U.S. It would be very difficult to provide it for any cheaper, considering the cost of the balloon (set by the manufacturer), 2 endoscopic procedures and related anesthesia, and nutritional support. 
There are other balloons in use elsewhere in the world. However, these do not have the evidence, safety profile, backing of rigorous clinical trials, and experience that Orbera provides. This may account for the very low cost of the quote you found in Puerto Rico. I would strongly advise against having a procedure of this nature in a different country in order to save money. We have had to help patients with balloons placed elsewhere, and their experience is generally not a positive one. 
I hope that helps answer your question. Good luck with your weight loss efforts.