£750,000 will buy you a house in London. Or an island paradise

Many people dream of owning their own tropical island, but for most it remains just a fantasy. Now, though, a slice of paradise has become almost affordable in Australia, with dozens of islands on the market and the global financial crisis driving down prices.

Off the Queensland coast alone, at least 11 islands are up for sale, with price tags reduced by nearly a half compared with a year ago. Some offer not only powdery-white beaches and crystal-clear waters, but all the accoutrements of a jetset lifestyle: mansions, swimming pools, twin-engine aircraft.

Fancy living like a film star? Julia Roberts tried to buy Turtle Island, in the Great Barrier Reef, eight years ago, but was pipped by a property developer. Now he is moving on and, having originally listed the 23-acre island for $6.75m (£3.52m), is said to be open to "any reasonable offer".

Perched on a hilltop on Turtle is an opulent residence, with its own guest wing, five bathrooms and a vast kitchen and larder, capable of "catering for the biggest celebrity party", according to the estate agents. The island has a helipad, pool and jetty, as well as numerous "toys" like motorbikes and inflatables. Its grounds are planted with botanical gardens.

Coming back down to earth, Turtle is still beyond the reach of most ordinary mortals, so, instead, how about Temple, a "boutique island", on sale for just $1.5m (£744,000) – the cost of a two-bedroom house in a fashionable area of London? While more modest, Temple has a private airstrip, and its four-bedroom house is surrounded by rainforest. Whales pass by twice a year; oysters can be plucked of the rocks; sea turtles nest on the beautiful sandy beaches. But be warned: the property "needs work", says Richard Vanhoff, of Coldwell Banker Capricorn Coast Realty.

Some islands on Mr Vanhoff's books are being sold because of family circumstances. "A lot of owners have had these islands for many, many years," he said. "They bought them as a nice place to bring up their kids and now the kids are finishing school or have left home."

He acknowledged that, with some islands on the market for more than a year, vendors were having to be realistic about price. "They probably came on stream at the wrong time," Mr Vanhoff said. "Islands are not recession proof. But there are still a lot of people out there with money who want that lifestyle." Most prospective purchasers are aged 35-55. According to Mr Vanhoff: "Some are looking for a sanctuary or getaway. Others would see it as a mark of success, proof that they've made it."

Island resorts frequented by well-heeled tourists are also changing hands. Last month, the Voyages company sold five Queensland resorts, including Dunk Island, off Mission Beach, for a huge percentage less than their valuation a year ago - with the price said to have been slashed from $51.8m to $25m (£13m).

Like other tourist destinations across Australia, the resorts have been hit by the recession. With visitor numbers down operators are struggling to fill rooms costing up to $2,000 a night, despite substantial discounts.

Industry watchers say it is difficult to attract buyers for such islands because, quite apart from tourism, they are hard to staff and expensive to run. Wilson and Heron, a pair owned by Voyages, were recently sold at knock-down prices, and Wilson is now available for rent at a relatively reasonable $3,830 (£1,983) per week. The Hunt Resort on Fitzroy Island, near Cairns, has likewise just gone on sale, after the company that owned it went into receivership.

Mr Vanhoff, ever upbeat, suggested Marble Island was a good buy at $15m, since it comes with two neighbouring islands. "So if you have three children, you could bequeath each of them an island."

Castaways: Celebrities and their island haunts

It's the ultimate bolt-hole for the paranoid celebrity: no refuge is more satisfactory than one from which would-be intruders can be spotted a long way off.

The actor Nicolas Cage got a taste for island life while filming Captain Correlli's Mandolin and subsequently bought his own island in the Bahamas. Princess Margaret famously fled to Mustique when it all got too much for her, where today non-royal honeymooners can rent a week of island bliss for $4250, including the use of a mule.

Richard Branson napped up Necker, also in the Caribbean, back in 1979, and has made regular use of it ever since.

The private island of cliché is usually in the tropics, such as Mel Gibson's Fijian hideaway of Mago. But some buck that trend, including the novelist Michael Ondaatje, with his island in Ireland's Mahone Bay, and the Indian yoga teacher Baba Ramdev, who has purchased Little Cumbrae on the west coast of Scotland for his devotees.