I was married 11 years ago in South America. Can i go back there and get a divorce since it is so expensive here?

You do not post if you have children or mutual real estate with the husband. If you do, the SA divorce may not be very helpful. If you don't you need to find out if the country where you intend to secure a divorce is a signatory of the Hague convention (this means the country and the USA agree to enforce each other's court decrees). I do not know if you will get suitable child support or asset distribution from a SA court. If all you want is a divorce, then you can use SA. If you want more, you may it much more suitable to use the Washington DC court.
LEGAL DISCLAIMER
Mr. Sarno is licensed to practice law in NJ and NY. His response here is not legal advice and does not create an attorney/ client relationship. The response is in the form of legal education and is intended to provide general information about the matter in question. Many times the questioner may leave out details which would make the reply unsuitable. Mr. Sarno strongly advises the questioner to confer with an attorney in their own state to acquire more information.

If there are no children and no property issues involved, and both parties agree, you could possibly get divorced in South America. However after 11 years of marriage, you may well have various issues and a South American divorce decree will really complicate things in the US should a dispute arise about pensions or property or other matters.