For us, it is the lifestyle, the weather and the sense of freedom from many of the aggravations of living in the USA. Yes, it is less expensive and that's a great benefit as well, particularly on a small retirement income. That said, you should have more than just Social Security and will need to meet the financial requirements of the FM3 visa. That now amounts to about $1300 USD per month, per person from foreign sources and you must prove that amount via bank statements at renewal time each year.