ASK ANY hypnotherapist. To relax a patient the image of choice is a desert island. The waving palms, the lapping waves, the sense of privacy, peace and safety. The internet means it's easier than ever to buy islands, some of which cost less than an average UK semi. But beware: island brokers are not always licensed.

Cheap islands are cheap for a reason. Take Cupid Island, a snip at $75,000 (£38,000). Though the details state an area of 4½ acres, it looks smaller, a bare sandbank just high enough to hold a shack out of the sea. The sales details acknowledge its limitations. “What it needs are coconut trees (which is actually not a problem since there are plenty to get from the town).”

There was worse to come. It's off Palawan, a part of the Philippines. Farhan Vladi, a leading island agent, says: “It's not legal for foreigners to own land in the Philippines.” This is a shame, because it puts me off the rather lovely Lemon Island, 7½ lush-looking acres off Guiramas, a veritable snip at $200,000. “You can form a consortium with a local partner owning 60 per cent and you owning 40 per cent,” he continues, “but you have to run it as a business.” What happens when you want to sell, though? Cheyenne Morrison, of Coldwell Banker Morrison, urges caution. “Titles can and have been forged. If your island turns out to be owned by the Government, the deal will be void.”

How about Fiji? Mel Gibson's recent purchase of the 5,411acre Mago Island for $15 million has been marred by legal challenges from the descendants of Fijians who sold it in the 1850s for 2,000 palm trees. In Fiji there are two native land Bills in front of parliament already. It's also politically unstable.

Would the waters be calmer across the Pacific in Tonga? Little Vavau Island, a tiny 1½acre rocky mushroom sticking out from the ocean, seemed too good to be true at $224,000. It was. No beach or anywhere to land on, and worse, on a 50-year government lease. “Always buy freehold,” advises Farhan Vladi, “and you'll need space to put in a septic tank, as you won't get a building permit without a plan for the sewage.”

Assuming the Caribbean would be too expensive, I looked near by: Belize, Honduras and Panama. “Costa Rica came up about 15 years ago,” said Ren Redmond, of www.private-islandsonline.com.

“Panama's very hot just now. Two hours from Miami and a prime area for retirement.” Isla Quiros looked good with 3½ acres at €450,000 but it was a fair way out in mid-Pacific. “It's important to be within 90 minutes of a hospital” said Vladi, “not just for you but also your staff.”

Staff? I hadn't factored them in. “It can get quite difficult for absentee landlords to remove squatters,” Vladi informed me. “After a certain number of years, title can revert. It is possible to buy an island with squatters already some way into this process, and a couple of island-owners have lost property this way off Panama.” I crossed the border south, to Nicaragua. Thanks to a civil-war-shaped dent in their property market, Pigeon Island was affordable at $285,000 and reared comfortably above the waterline: 7½ acres, including “two old wells and one wind turbine (no tower) . . . not to mention tons of beautiful rock to use in concrete construction”. Vladi wasn't impressed. “You can tell these Central American properties aren't owned by island lovers: none are developed. They just switch around between greedy businessmen. Real estate in the US is in crisis just now; in a year's time you'll be able to buy these same islands for half the price.”

My stretched Spanish was stranding me in hot waters. Ren Redmond suggested I might be more at home in Anglophone Belize. At $375,000, Lark Caye was four acres, not all dry, but apparently the soggy bits could be filled with sand, and interestingly laid out around a central lagoon. Ideal, I thought, for sheltering a yacht. Then I found a mother-lode: the stable democracy of the Bahamas. Kevin Cross, of Bahamas Realty, said “We haven't been affected by the US downturn: I think people see our islands as a refuge from the market. I've got a 1½acre rock for $375,000 so close to Abaco Island that you could throw a stone across, and houses on Abaco go for more than a million. It's a bit small though. I'd recommend two-acre Little Gaulding Cay for $600,000. If you ran in services, you could definitely make money: there's a much bigger demand for developed islands.”

At last. An estate agent who spoke my language: profit and greed. The 2,250 islands and cays of the Bahamas shelter 400 international banks, but I imagine they are more concerned with hiding money than lending it to me to buy my dream island. But I had a plan. I'd spotted another ad, back in Belize, for Cockroach Cay. Buy that, change its name – Bonefish Beach might hook an angler – and flip it back on the market at a higher price. That should raise the cash. Quickly, though. Undeveloped islands can take years to shift, but if Vladi was right I wouldn't have that long.

FACT FILE

- Hire a local lawyer, but make sure that he or she is competent and honest.

- Stay a week before you buy. You may find snakes, sandflies or squatters.

- Seek local advice on ownership disputes and prevailing winds.

- Survey structures, especially jetties, carefully (salt water causes rot).

- Fresh water is vital. Desalination plants are expensive, require maintenance and use a lot of power. Test wells by draining them and seeing how long they take to refill. Harvesting rainwater in tropical regions may see you through the year.

- Most island brokers can be found on:

- www.vladi-private-islands.de

- www.privateislandsonline.com

- www.bahamasrealty.bs

- Lark Cay is handled by www.caribbeanislandbrokers.com

- Tonga: www.vavaurealestate.com

- Philippines: www.philippines-real-estate.com