At 68, Barbara Miller Elegbede is living proof that flower children need not grow up.

A self-described hippie, she attended a San Francisco college at psychedelia's height and remembers friends constantly crashing on the couch of her apartment, just a block away from Janis Joplin's pad in the hip Castro neighborhood.

Now retired from teaching and secretarial work, Elegbede, 68, has become a full-time "couchsurfer" herself, living in other people's guest quarters all over the world. (She has a temporary apartment in Tempe, Arizona.)

"I've lived in Africa. I know how to take a bath from a bucket ... I've lived in caves in Greece and hitchhiked all over the world. Next year, I'm off to India for two or three months."

Call Elegbede one of the "rambling retirees": folks who give up the senior community or a comfy house for a life of constant travel. And they're not all hippies.

"The RV (recreational vehicle) has replaced the rocking chair, and the whole notion of retirement has changed in the last 10 years," says Ken Budd, executive editor of AARP magazine and author of "The Voluntourist: A Six-Country Tale of Love, Loss, Fatherhood, Fate and Singing Bon Jovi in Bethlehem."

There are no good statistics on just how many boomers are taking retirement on the road. But some indicators - steadily rising traffic at houseboat and recreational vehicle websites, and a growing number of retirement-age members on couchsurfing.com - confirm the trend.

There are two drivers, according to journalist Samantha Dunn, who's written about RV retirees for the website Next Avenue. First, wireless technology means you can easily stay in touch with friends and family even while living on the road.

Then there's the financial angle. Today's retirees have limited budgets and long life expectancies. Living on the road for a year or five can be a way to spend less than hanging on to the big house or moving into a service-heavy retirement community.

"Even if you buy the $100,000 RV rig, it's cheaper than dealing with an oversized house and taxes and all the things home ownership entails," Dunn says.

Folks who have done it agree. John Graves, editor of the Retirement Journal and author of "The 7% Solution," a book about financing retirement, spent 10 years without a fixed address and traveled to 80 countries. By living simply, bartering and eating from street vendors, Graves, 64, says he saved the equivalent of $36,000 annually.

If that's sounding good, read on. Here's what it takes to retire on the go, whether you choose to hang your hat in a houseboat, a mobile home, or on the back of someone's sofa.

DIFFERENT STROKES: FREESTYLE

Couchsurfing is the practice of moving from home to home, sleeping in whatever space is offered gratis. Of the almost 5 million members at couchsurfing.com, some 160,000 are over 50 years old; their ranks have at least doubled since 2009. Accommodations can range from a weathered futon in someone's living room to a yacht bunk or a Maui tree house. Typical stays last two to three days but can also last several months. While you can reciprocate and offer your own couch when your host travels, there's no requirement that you do so.

Lodging comes free, though extended stays in a city may mean side trips to a hostel or hotel while hopping between host homes. Elgebede says she can stay in South America for as little as $1,200 a month, or China for $1,500, including eating out.

Couchsurfing.com has a group for global couchsurfers over 50 years old with 145 members, up 7 percent from a month ago. It includes members from all over the world, including Iran, Argentina, Uzbekistan and the Ukraine.

AFLOAT AND LAID-BACK

As many as 9,000-plus people have retired to houseboats in the United States and Canada, an estimate based on statistics collected by the Center for Competitive Analysis of the University of Missouri.

Some houseboaters float from dock to dock, though many stay in one place on the water. People who call themselves "liveaboards" have a leisurely life marked by sunbathing and grilling.

Houseboaters vary as much as the retirement population itself: upscale and downscale, singles and married couples, serious sailors and novice boaters, says Ian Morton, editor of the All About Houseboats website. Many are concentrated on Kentucky's Lake Cumberland, affectionately known as the "Redneck Riviera."

A used boat for a couple, plus room for guests, will cost $50,000 to $250,000, Morton says. The same boat new ranges from $200,000 to $1 million, and amenities can include dishwashers, garbage compactors, a full kitchen and even a hot tub.

Morton, 51, is semi-retired and lives on a houseboat six months out of the year in Montreal, Canada. (He also travels in an RV and has an apartment.) His major annual costs are insurance ($2,000 for a $200,000 boat) and docking ($3,000 and up).

A marine survey for your floating home to ensure its shipshape can run $1,500 to $2,000. First-year costs typically run $25,000, including maintenance and fuel, says Morton, citing the survey and improvements to a newly acquired boat. Annual costs may drop 20 percent or more in subsequent years, assuming a lack of weather damage or major repairs.

Morton, who's saving thousands of dollars annually compared to a land-based life with a mortgage, plans to live on a houseboat as long as he's able.

"It's peaceful, everybody's in a good mood, you get to fall asleep with the rocking of the waves and the wind, and with the Internet, you can home-office from just about anywhere."

Informative websites include Houseboat magazine (houseboatmagazine.com), Boat Owners Association of The United States (boatus.com) and All About Houseboats (all-about-houseboats.com).

DESPITE FUEL COSTS, RVS REMAIN POPULAR

Estimates vary on how many retirees live in RVs year-round, but it's probably north of 25,000, based on data from the Escapees RV Club and the Recreational Vehicle Industry Association.

Large variations exist in RV price, says Jaimie Hall Bruzenak, co-editor of the RV Lifestyle Experts website and co-author of "Retire to an RV: The Roadmap to Affordable Retirement."

A used Class A RV, manufactured on a large truck chassis, can run from $10,000 to $150,000. Some top out at more than $1 million. The Lazy Daze, a Class C motor home (built on a cutaway van chassis), is especially popular. It sells in the $100,000 price range new, or as little as $5,000 used.

RV expenses top out at $14,000 per year, calculates Rich Arzaga, founder and CEO of Cornerstone Wealth in San Ramon, California, who just took an extended RV vacation with his family to sample the lifestyle.

Costs include campsites, which average about $30 a night, and gasoline: Expect to spend around $300 to fill a 74-gal. tank. Insurance can run $2,000 and storage an additional $1,000 annually.

With housing costs for renters and homeowners averaging $16,557 (according to the U.S. Bureau of Labor Statistics), living in an RV is actually cheaper by at least $2,500 annually, says Arzaga. "Full-time RV travelers can also choose their state of residence, and eight states have no income tax."

Informative websites include RV Lifestyle Experts (rvlifestyleexperts.com) and the Escapees RV Club (escapees.com).

Many retirees living in RVs, such as Fran Reisner, 52, suggest towing a car to explore back roads.

"I have a Honda CRV, which happens to be one of the easiest to tow," says Reisner, who paid $92,000 for a 35-ft. Winnebago Adventurer in a high-stakes trade-in: life at home in Frisco, Texas, for life on the road, indefinitely.

Her rolling home has a king-size bed, double-wide refrigerator and a washer-dryer.

Reisner says RV life has worked out well financially, and she has no plans to give it up. Having just hit the one-year mark, she's logged 18,000 miles across 27 states. And countless miles of exploring remain as life takes her down a new road: photographing nature and wildlife.