With median home costs now exceeding $250,000 in many places around Puget Sound, it's hard to believe that a house — and a brand new one at that — can be had for $100,000 or less. Is there a catch?

Of course there is: Land cost is not included, and the house may not exactly be a house. Rather it could be a log cabin or even a fabric-covered yurt (but one big enough to include a loft).

These are among the affordable-home possibilities on display at the Seattle Home Show. Each home is a full-size structure on the show's Idea Street. Show promoters say it's the only one of its kind at any Home Show in the nation.

"The big deal is you can actually see the homes finished, landscaped and furnished, so it gives you a ton of ideas for what you can do," said Michael Kalian, Seattle Home Show managing director.

Even sans the land, there are plenty of potential buyers. They include people hoping to construct a vacation getaway or an economical private residence. Other candidates are homeowners looking for an easy way to add on to their existing home; they can find it in a preplanned, small structure that can be attached to their house.

"You have many choices: manufactured home, log home, stick-built home, modular home," Kalian said. "There are people there at the show who can give advice for whether a particular home will work on someone's land."

Among the homes on this year's Idea Street are:

• "The Harborside" built by Timberland Homes of Auburn. It's a 1,310-square-foot cottage — two bedrooms, each with its own bath, a great room and kitchen. An optional screened-in porch adds 300 square feet of living space.

"We envision it as a place at the ocean or at the San Juans where one family may own it or possibly two," said Bill Marr, Timberland's director of sales and marketing. "We're seeing more of that — families going together to buy. [The Harborside] has a great room where everyone can gather, but each family has its own master suite."

The house, constructed in modular sections in Timberland's Auburn factory, is built to the same International Building Code as site-built homes.

The 1,310-square-foot Harborside model home, manufactured by Timberland Homes of Auburn, has a base price of $149,800. The house, constructed in modular sections in Timberland's Auburn factory, is built to the same International Building Code as site-built homes.

"It's a stick-frame, off-site built house," Marr explained, that's put together on the owner's lot in 90 days.

The base price of the Harborside model is $149,800. The Home Show version, which features custom options such as granite, glass tile, upgraded cabinets and exterior shingles, is priced at $232,800.

• Cascade Mountain Log Homes' three-bedroom rambler. For $72,900, buyers get an 1,800-square-foot log home highlighted by a great room with three log trusses. Included in that cost is the log-shell system, but not the foundation, interior finishing or wiring, plumbing and heating systems. Company owner Ted Boyd estimates that finishing it would add another $160,000, more or less, depending on whether the owner could do some of the work.

The display model was made of 9-inch, hand-peeled logs in the firm's headquarters in Startup, Snohomish County. Like all of Cascade's log homes, it's made of dry-standing dead timber, commonly Engelmann spruce and lodgepole pine, that's naturally seasoned before harvest. Besides three bedrooms, the home has two baths, a great room, a kitchen with an eating area and a front porch.

The typical buyer, said Boyd, is someone who's had a log home in their family and enjoys the warm look of natural wood. Many are purchased as recreational or retirement homes.

• A yurt by Rainier Industries of Tukwila. Centuries-old in design, a yurt is a circular domed tent. This one, the "Eagle" model, is 21 feet in diameter and almost 13 feet tall — enough to add a loft. Its 338 square feet can be finished to include a kitchen and living area. Base price is about $7,000, according to Jessica Morgan, marketing manager for Rainier Industries. The show model is $18,000 because it's been customized to include French doors and other amenities.

"People use them as vacation homes and as ski huts because they have very high snow and wind loads," Morgan said.

Other buyers have used them as backyard home offices, and larger ones are used as primary homes. (Cirque du Soleil is a customer.)

Included in the base price is a round, post-and-beam constructed platform, a wood lattice "wall" system, rafters and an outer fabric covering made of heat-sealed panels.

"It's a specially designed fabric that doesn't have to be supported every inch of the way," Morgan said. The yurt can be insulated and heated with an electric stove. Founded in 1896 as Puget Sound Tent and Awning, the company that became Rainier Industries started out making tents for Alaska's gold-rush miners.

• Palm Harbor Homes' "Mt. Shasta" model. This 2,428-square-foot Craftsman-inspired home comes out of the Oregon factory of one of the nation's largest manufactured-home builders. It has three bedrooms. The master suite's bath has a tile shower and a soaking tub. There are separate living and family rooms, an office retreat off the master bedroom, a breakfast nook and a butler's pantry. It holds Super Good Cents, Energy Star and Earth Advantage certifications.

COURTESY OF PALM HARBOR HOMES Palm Harbor Homes' Mt. Shasta model home is at the home show. The base price for this three-bedroom home is $109,252; the home-show model version is $144,664.

The Mt. Shasta's base price is $109,252. The Home Show model — including all appliances, window coverings and set-up on the buyer's lot — is $144,664.

According to Curtis Richards, Northwest marketing director for Palm Harbor Homes, the typical buyer is in his or her mid-40s and buys the home as a primary residence.

"They're trying to make a decision on whether to build a site-built home or buy a custom manufactured home," Richard said. "A couple of things tip them in our direction — the ability to customize the floor plan and the cost.

"The factory is acting like a giant sub. We're building a huge portion of it inside a controlled environment."

• Aurora Quality Buildings' two-bedroom cabin. A family-owned business based in Marysville, Aurora Quality Buildings will have five buildings at the Home Show. They range from garden sheds up to an 800-square-foot cabin that sells for about $25,000.

The cabin consists of a central 14-by-24-foot room tall enough for a sleeping loft, two 10-foot-square bedrooms and a deck. An all-wood product (no particle or press board is used), it's sold as a shell and built on site.

"We specialize in getting the structure up, then the homeowners finish it out themselves, and that saves a lot of money," said Ward Holmes, company owner and president. He estimates an additional $20,000 would cover the cost of the cabin's foundation, plumbing, wiring, heating and interior amenities.

The typical buyer uses the cabin as a vacation getaway, guest house or office. Others use them as home additions.

"It tends to be an affordable way for people to get more space," he said.

The Seattle Home Show is co-sponsored by the Master Builders Association of King and Snohomish Counties.

Elizabeth Rhodes: erhodes@seattletimes.com