(FORTUNE Small Business) – If you've got an extra $45,000 to burn, you have a couple of appealing options. You can send an orphan to Harvard for a year. Or you can grab some pals and spend a night--that's one night--on Musha Cay, a 150-acre private island in the Exumas chain of the Bahamas that offers the perfect getaway for those bored by the plebeian charms of St. Bart's and Mustique.

Not that anyone's being judgmental. Indeed, when asked to investigate the bang-for-buck ratio on Musha Cay, I found myself suddenly untethered from my usual preoccupation with égalité. I began packing and was adjusting nicely to the prospect of interrupting an oceanside massage long enough to reach for a canapé when the inconceivable happened. That little upstart Faith Hill and her crooning cowboy consort, Tim McGraw, grabbed the entire island for the week--the going rate is $43,150 a night for as many as 24 people--leaving me to track cake crumbs elsewhere.

As it turns out, private islands for rent aren't hard to find. Nor are most as expensive as Musha Cay, possibly the priciest of all (see box). At the lower end--if privately owned islands can be characterized that way--are places such as the appropriately named Money Key, 25 miles off Key West, which goes for as little as $5,800 a week for two. Or Pirate's Cove Island, also in the Florida Keys, at $3,400 to $4,300 a week for three people. (Most will allow you to bring extra guests at a per diem increase. Pirate's Cove, for example, charges an additional $300 to $400 a person for each day, depending on the season.)

By a quirk of fortune or fate, I found myself bumping along a soggy dirt track on Guana Island in the British Virgin Islands, a comparatively bargain-basement island at only $15,000 a night for as many as 30 people--or $850 a night for double occupancy during the high season (Dec. 16 to April 15), a price that includes meals and a (very) few necessities.

Guana, a protrusion of which resembles an iguana's head, may be the answer to Existential Man's search for authenticity. It's the getaway for those who need to get away from getting away. Possible brochure ads: FRED AND WILMA'S DREAM VACATION. Or IF HIPPIES HAD MONEY. To get there, you first fly to San Juan, Puerto Rico, then take another 40-minute flight to Tortola Island, from which Guana is a ten-minute boat ride. As I arrived on Tortola, the customs inspector examined me with palpable contempt when I said I'd be staying just two nights. Can't be done, he told me. You can't see all of Guana and write a story after only two nights.

Can too. You can cure cancer, write a novel, and compose a symphony in two nights and one full day on Guana, because there is nothing else to do. Which is entirely the point. As one frequent visitor explained to me, "You don't come to Guana to do; you come to Guana to be." Yes, Grasshopper.

Captain Michael met me at the Tortola dock and ferried me to Guana, where Roger, half of the British managing team of Roger 'n' Bridget, greeted me and took me up the hill to my quarters. In the interest of privacy, one does not use surnames on Guana. Whether you reveal your full identity to others is your prerogative, but Roger and Bridget won't give you away, which is handy if you happen to be a celebrity, or wish to seem like one.

Travel on the island is by boat, foot, or golf carts that zip along winding dirt paths deeply reminiscent of Jurassic Park. I kept waiting for puddles to ripple as T. rex made his way through the salt flat, past the six flamingos that won't mate ("We think they're gay," says Roger) and the abandoned sugar mills once run by Quakers who settled here in the 17th century. The only sounds are the surf, the island's 50 species of birds, and the sudden rustle of underbrush as something--a baby velociraptor?--skitters away.

How to put it? Guana is the sort of place where you half expect to bump into a small Chinese man singing to a papaya tree. Wait. There is a small Chinese man singing to a papaya tree. His name is Dr. Liao Wie Ping, resident ornithologist and head gardener, recognizable by his green helmet, the machete that seems permanently affixed to his right hand, and of course his musical odes to whatever captures his fancy.

"Everyday I here, I'm feeling good, I happy man," says Dr. Liao, who has lived on Guana for almost 20 years. "I love the nature. I see a rock and I have a song. I plant a banana tree, I have a banana song. I plant a mango, I have a mango song." And then he launches into poetry and melody, first providing the lyrics in English, then singing in Chinese.

No one would doubt Dr. Liao's joyous sincerity. Nevertheless, I couldn't help considering that the diminutive bird man has been singing songs in Chinese to credulous tourists for a long time and that his lyrics might really translate into something like this: "I am singing another goofy song / To these smiling morons / They think I love my papaya / And I do / But I love tricks most of all / And I have the machete."

Such is "being" on Guana. As for doing, okay, I exaggerated. You can swim, sail, snorkel, hike, read, fish, play tennis and croquet, or get a massage. (Anything involving major equipment, such as scuba-diving or deep-sea fishing, costs extra; massages will run you $100 an hour.) But you definitely can't shop. Or play golf. Or watch television. Or talk on a cellphone, at least not in front of other guests. (Wireless service works on a couple of plans, but it's understandably sketchy.) If you must indulge your obsessive-compulsive nature by staying in touch with mainlanders, island etiquette demands that you do so in your own space. The chances are good you won't long need the contact. According to island lore, one high-stress city dweller who came to Guana hovered over the office fax machine his first day, and did so on the second too, but somewhat less diligently. When notified on the third day that a fax had arrived for him, he shrugged and indicated with two words--not "Merry Christmas"--that the world was no longer his concern.

"Grasshopper," who typically spends two consecutive weeks on Guana, put it this way: "On day three, you're relaxed. On day seven, you're Jell-O. By the end of the second week, you don't care if you ever go back again."

The island's ethos, explains Roger, "is a rollback of convenience and of what you expect." When I suggested that a coffeemaker in the room would be nice, I didn't anticipate just what a dimwitted idea that was. Roger is first a manager, second an engineer, and from his perspective as custodian of two mega-generators and 38 internal combustion engines, 16 coffeemakers means 16 requests for cream, which necessitates 16 refrigerators, which equates to 16 more problems. I feel so stupid.

Guana is admittedly exquisite. Lush and unspoiled, it features about a dozen whitewashed stone buildings nestled into the hillside, mostly cottages with bright-blue shutters, and all with a private deck overlooking the water. The island belongs to the arrogantly shabby school of resort design--paradise for those who eschew luxury for authentic experience. Owners Henry and Gloria Jarecki of New York, who bought the island in 1975, are committed conservationists who've restored the ecosystem, reintroducing the once indigenous iguana and flamingo, and open the island each October to scientists for research.

Rustic and unpretentious, rooms are simply appointed--bed, wicker chest, desk, and chair. No TV, no radio, no clock, no hair dryer. No air conditioning. (I didn't miss it.) Bathrooms feature an adobe-style free-form shower sans curtain. Otherwise, the only amenities are Crabtree & Evelyn soaps and shampoos and a large can of Off, which is second only to oxygen among required items. Did I mention the mosquitoes?

As luck would have it, the week before I arrived Guana Island was experiencing a rare monsoon--28 inches of rain in ten days, which put much of the island's roadways and Dr. Liao's beloved orchard underwater. Grasshopper assured me that he'd never before used bug spray on Guana, and I believe him, just as I believe that there really is a friendly four-foot iguana named Cheepa who periodically emerges to be hand-fed by visitors. All I know from personal observation is that during my two-day stay I shared the island with a lot of mosquitoes and only one smallish iguana, who indicated by a certain sidewise glance that we would not be supping together.

When dinnertime does arrive, you have a choice of dining with other guests, in which case Roger provides a rotating seating chart, or eating separately on one of the private terraces. Guests dress casual chic for dinner (these are the British Virgin Islands) and rendezvous by torch and candlelight for cocktails and hors d'oeuvres in the clubhouse (think teak, sea grass, and rattan). The building becomes magical at night, opening up on both sides for breezes and panoramic views of the Atlantic and the Caribbean, as well as providing a fly-through for smallish bombardier birds. Drinks are self-serve in the honor bar, and though the wine offering is thin, the multicourse menu does not disappoint: plantain-and-christophine soup (they're starchy tubers), seafood Thermidor, saffron rice, steamed snow peas, carrots with thyme, chocolate tart with butterscotch and almond sauce.

Evenings are apt to end early because time on Guana is a relative concept, and nature's cycles tend to subsume such human conceits. You are, alas, tired to comatose by sundown if you've lived right on Guana. I don't know how Faith and Tim spent their week on Musha Cay, and after spending approximately 45 Zen-filled hours on Guana, I didn't care either.