More than 150 years ago a popular phrase urged Americans with unlimited financial prospects, "Go west, young man, and grow up with the country."

Today it's more like, "Go south, old man and you may outlive your money in Mexico -- or Costa Rica."

Retirement abroad used to be the purview of the well-to-do -- a luxurious reward of exotic locations, expanded horizons, prolonged travels and a life without schedules.

These days it's a matter of survival, or at least a rather drastic financial maneuver to make a dwindling nest egg last longer.

"It used to be divided between having an adventure and being able to go someplace affordable," says Rosanne Knorr, author of "The Grown-Up's Guide to Running Away from Home: Making a New Life Abroad."

"But I'm getting more and more questions about where are the most affordable countries you can go," she says.

In Central and South America, the cost of living is one-third to two-thirds what it is in the U.S., says Barry Golson, editor in chief of ForbesTravel.com, who with his wife, Thia, authored the upcoming "Retirement Without Borders."

"You can have a little house with domestic help and gardening help and you get more for your money," he says. "That's useful for people who are facing tougher times here."

But there are trade-offs. You have to be willing to live in a place that likely has different standards, mindsets and policies. And you also may be quite a distance from family, friends and familiar surroundings.

"If you have family at home and have grandchildren, you really have to think twice," says Golson. On the other hand, he says, if you retire to "an exotic location, it may be easier to have them visit you." Especially if your new home doubles as a cheap vacation destination.

The money aspect
There are also two big money factors to consider: the exchange rate in the country you move to and the cost of living in the specific locale you're targeting. For example, with a tough exchange rate in France and Italy, retiring to Provence, France, (which includes such cities as Cannes, Nice and Saint-Tropez) or Tuscany, Italy, (Florence, Sienna and Pisa) is out for many people. But, if you have at least $50,000 a year in income, some areas, like Languedoc (just west of Provence) or Umbria (just east of Tuscany), may still be doable, Golson says.