Housing that Moves . . . and provides, at low cost, the look and feel of a complete home

I met Cynthia Durgin in the office of Russell Legare here recently. She sells TV commercials for a living; he sells mobile homes.

The two were working on the format for an ad and her heart was in this one even more than usual. As the owner of a mobile home, she felt the rest of the world should know what ''practical, comfortable, pleasant, affordable, durable, and now good looking'' housing the mobile home provides.

Legare, a former member of the Canadian team to the World Cup ski championships, was pointing up some of the pros of mobile home ownership when Mrs. Durgin's unrestrained enthusiasm for the homes took over.

Her home, 14 feet wide by 70 feet long, comfortably houses her family of four (husband and two children). She finds it better laid out and consequently ''more spacious'' than the larger conventional house the Durgin family formerly called home.

The Durgins' home is sited on their own plot of land; a garage has been added , linked to the home by a breezeway. This has provided them with all the storage room they need and given the home a most conventional look.

In fact the term mobile is almost a misnomer for this type of housing as only 2 percent of the 5 million units nationwide are ever moved; the rest are permanently placed in a mobile home park or on private lots.

Harold Kelley of Weymouth, Mass., owns what he terms one of the ''new generation'' of mobile homes with hip roof and conventional siding. It even has a modified cathedral ceiling in the living room. Inside or out, it is difficult to tell it from a conventional house. It is somewhat shorter (60 feet) than the Durgins' house, but when you include the optional extras - a ''tip out'' or bow-window addition to the living room and an add-on room at one side - the house boasts a clear 1,000 square feet of living space.

When he retired a few years back, Mr. Kelley opted for a mobile home because ''maintaining a seven-room house was more than I could do on a fixed income.'' Leaving a beautiful old home wasn't easy, he says, ''but now we live in a beautiful modern home and I'm not pushed to the wall financially.''

Mr. Kelly sees the mobile home as ideal for retirees and also for young folk ''who don't have all the money in the world to get started.'' The mobile home's flexibility, with add-on rooms, tip-outs, etc., means the home can readily grow as the owners' financial position improves.

The Durgins and the Kelleys also enjoy the fact that the solid, well-insulated construction of the modern mobile home results in low annual energy bills. The use of largely corrosion-proof rot-resistant materials also means that ''maintainance on our home is minimal,'' says Mrs. Durgin. The net result, she adds, is that other financial obligations of the family have been met with ''much less difficulty'' than would otherwise be the case.

The mobile home still makes up a tiny fraction of the housing market. But it is a growing one, spurred by skyrocketing costs of conventional homes, high interest rates, vastly improved quality and design, and a slow but steady breakdown of old prejudices by both the buying public and zoning board officials.

Time was when the mobile home looked and often was no more than an enlarged version of the travel trailer used by campers on summer vacations. To many mobile homes suggested a ''gypsy style'' of living. Formerly, too, trailer homes were often looked on as a temporary form of shelter. This approach was reflected in poor construction quality. Today federal regulations mandate minimum standards in the construction of mobile homes. Says Robert Williams, vice-president of Poloron, a major manufacturer of modular housing and mobile homes in Middleburg, Pa.: ''Everyone left in this business today (the recent attrition rate has been high) makes a good quality product. Those that didn't are now out.'' His company, he says, makes mobile homes ''to the same exacting standards we apply to our modular units.''

Time was when the purchaser of a mobile home took depreciation into his calculations much as one does with the family car. Not so any more. Harold Kelley, who paid $25,000 for his mobile home five years ago, was offered $34,000 recently. Mr. Legare recommends that mobile-home owners who own their own land add garage, breezeway, and garden shed, as and when they can ''to create the look and feel of the complete home at a lot less cost.

The major saving in a mobile home,'' he points out, ''is doing away with foundations or footings.'' Where the average cost of a conventional new house currently runs at around $45 a square foot, the mobile home comes in at around $ 19 a square foot. At the lower end of the price range, mobile homes run for about $12,000 with top models costing more than $50,000 in some instances. Size and the optional extras make the difference.

What is the principal drawback to owning a mobile home? Finding a place to put it, says Mr. Legare. There are regions in Maine, for instance, ''where you can erect a tarpaper shack but you may not put a $20,000 mobile home on your land.'' But this is changing. The trend in housing legislation is to rule that districts may restrict the placing of mobile homes to certain areas but may not exclude them altogether.