(FORTUNE Magazine) – ESCAPISTS DAYDREAM ABOUT them; James Bond's enemies use them for evildoing; most of us spend a week or two on one of them every chance we get. No wonder: Islands are both a natural fortress--especially when surrounded by rocky shoals--and a psychological one. And you need no surveyor to demonstrate where your patch of earth ends and your neighbor's begins. On an island you can stand on the highest point, gesture across the landscape, and declare to no one in particular, "Someday, all this will be yours!"

Celebrities, of course, have long repaired to island getaways to recover from various fame-induced maladies. Marlon Brando made the French Polynesian atoll Tetiaroa his hideaway; more recently Johnny Depp bought one in the Bahamas. But you needn't be a billionaire recluse to live like one. In the current market, islands--ranging from a few hundred thousand dollars into the millions--may be one of the last bastions of affordable real estate. Consider: In tourist-choked hot spots such as Malibu and the Hamptons, waterfront prices have tripled over the past five years, according to Dolly Lenz, a broker with Prudential Douglas Elliman Real Estate. Says Scott Donley, an automotive industry executive who has been hunting for waterfront property: "In Malibu, things were starting at $6 million to $7 million, and that to me is obnoxious." He looked in South Florida near Naples as well, but found tear-downs topping $2 million. Now he's turning his search to islands in Belize and the Bahamas. "Given all that, an island is a hell of a bargain," he says.

Okay, so "bargain" is a relative term: Building and living expenses aren't exactly minimal when you're waterlocked. But "in a sense," says megabroker Farhad Vladi of Vladi Private Islands, "it is easier to develop an island than it is a piece of property on the mainland. After all, on your own island, there are no neighbors to deal with." And once out-there alternative energy sources like solar and wind power are getting cheaper, while a decent desalinization plant for drinking water now goes for around $20,000. (Caution: If the term "desalinization plant" strikes fear into your heart, you should stick to the mainland.)

If you're looking to buy, you'll need a broker--most inventory is controlled by a cadre of them (Vladi, Cheyenne Morrison of Coldwell Banker Morrison's Private Islands, and Kevin Cross of Bahamas Realty Ltd. are three of the biggest). The hottest market right now is the Bahamas, where islands are selling fast and have appreciated dramatically. Belize and Panama aren't far behind. Bargain hunters, though, should head north: In Nova Scotia and British Columbia, a few hundred thousand dollars buys an island and a house. Here in the U.S., check out Maine, the Florida Keys, and freshwater islands from New York to Michigan. Whether you want to rough it near the equator or hop to work via helicopter, we found seven islands that will satisfy any waterfront fantasy.

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