I believe in the States Alabama would be the cheapest place to retire to. Alabama has one of the lowest cost of living I believe there was a study awhile back that stated $100 is equal to approximately $115 in Alabama. Social Security and pension income are not taxed in Alabama all other retirement income are. State income tax is 5% which is higher than neighboring Florida but your cost of living is far lower in Alabama which should offset this.
May want to check out Vietnam as another country to retire to. There is a capital gains tax you have to pay but I believe it is rather small. Cost of living is extremely low in Vietnam. Thailand is another option similar to Vietnam.
Poland is a good country to move to though you will need to learn Polish as English is not spoken all that much. You may be able to get away with speaking German but you would probably want to pick up some Polish at least.
Panama is another country you may want to look into. Panama is home to basically every country in the world. You can find Americans, Venezuelans, Chinese, French, Koreans, and other communities in Panama.