Prince George's County needs a bigger supply of larger, more luxurious homes to retain and attract home buyers who are moving to neighboring counties where they can find a better variety of housing, according to a study by a local real estate research firm.

Legg Mason Real Estate Research said Prince George's is turning away potential buyers searching for more elaborate homes, including executives who are working for the increasing number of high-technology and telecommunications companies in the county.

"We needed to find out what could be done to encourage more builders to develop this kind of housing," said Dennis C. Murphy, chief executive officer of the Prince George's Economic Development Corp., who commissioned the study. "What's most revealing about this study is that executive housing is many things to many people."

The study also said the county needs a quality shopping mall and needs to develop a wide range of housing, ranging from luxury apartments and condominiums to upper-end town houses and larger single-family detached homes, to encourage its workers to stay in the county when they buy new residences.

Within the past four years, the report said, the county has attracted more builders who are constructing projects with homes that sell for more than $150,000. In 1984, the county had two tract projects with homes that sold for more than $150,000; in 1987, there were about 20 such projects, according to Legg Mason.

The average executive or upscale home in Prince George's costs between $175,000 and $225,000, the report said. They are primarily single-family detached homes with three or four bedrooms, 2 1/2 bathrooms, two-car garages and family rooms. In Fairfax and Montgomery counties, similar homes are at least $30,000 to $40,000 higher and luxury homes in those counties cost between $300,000 and $1 million.

One of the major problems Prince George's has had in attracting luxury-home developers is the negative perception many prospective buyers still have about the county. According to the survey, many real estate agents overlook the county as a place for new Washington area executives, possibly because of lower housing prices, which translate to lower sales commissions, or their lack of knowledge of the county's demographic make-up.

"The county has labored over some image problems," said Robert Kleinpaste, president of Legg Mason Real Estate Research. "But the county needs to do more to tell people about some of the good things it's doing. Many of the developers, builders and executives interviewed said they hadn't realized how successful the county was in attracting businesses to the area over the past five to seven years."

Kleinpaste said the study also showed the county needs what local residents and corporate executiveswould perceive as a quality shopping mall. The county is losing a significant number of shoppers and sales tax revenue to other counties, he said. Mark Vogel Cos. and Edward J. DeBartolo Corp. are developing a mall at the Bowie New Town Center, but that won't be completed for at least four years.

Prince George's does have several advantages over some of its neighboring counties, however.

The county has lower land costs, a large supply of zoned land and good access to major roads, such as the Capital Beltway, Pennsylvania Avenue and a soon-to-be upgraded Rte. 301. It also has a large percentage of residents who work in the county, and an even larger work force is projected within the next five years. An additional 18,000 jobs are expected to be created by 1990, the study said.

Largo, Bowie, Laurel, College Park, Tantallon, Greenbelt and Upper Marlboro are the key areas where much of the new residential and commercial growth is occurring. Some of the newer development in these areas is much more aligned with the kinds of housing Prince George's needs, the report said.

The Bowie area has one of the largest concentrations of higher-income residents in the county, with 43 percent of all families earning more than $50,000, the study said. As a result, more families can afford larger, more expensive homes. In 1986, the county had 15,800 households with an average income of $75,000, as well as $50,000 in equity (either in cash or in their existing home), which meant that they could afford a $260,000 home. By 1991, 38,200 households will be able to afford a similar home, the study said.

Gary Thatcher, vice president of Ryland Homes' Chesapeake division, said the company is seeing a greater demand for larger houses. For years, the company built homes that cost between $70,000 and $90,000. The company is now building homes starting at $190,000 at several developments in Prince George's.

"The county is almost a sleeping giant," Thatcher said. "Things are going to get better in the county as time goes on because, slowly but surely, people are looking at Prince George's County as an alternative to the other counties."

In Lake Arbor, one of the county's largest and more successful planned community developments, houses sold for between $125,000 and $160,000 in February 1986, prices that even the project's developers thought were a bit too high. But the houses sold, and now, Gary Lachman, senior vice president and chief operating officer of the mid-Atlantic region of Community Holdings Corp., the community's developers, said that many of its homes are selling for between $180,000 and $225,000.

Last fall, the Shannon & Luchs-Kossow Development Group began building one- and two-bedroom luxury apartments at a project called Lake Arbor Towers that will rent for a minimum of $650 a month. "We're going to have to provide the best of all" kinds of housing, Lachman said.