Peter G. Miller, who conducts seminars in how to sell houses without using a realtor, estimates that some 300,000 Americans sold their houses on their own last year. Not everybody can do it, he says.

Preparation is a big factor, because "the buyer is relying on you for information on the current mortgage market, whether the loan is assumable, taxes in the ares," etc., he said. In addition, people who can sell are, "ideally, those who are prepared to fix up the house themselves, or willing to hire someone to do it."

He compares the hiring of a real estate broker to sell a house with the use of a certified public accountant to prepare taxes: some people can can do both on their own.

In partnership with local attorney Benny L. Kass, who has specialized in housing and consumer matters, Miller has set up something called the Consumer Information Institute, which operates out of Kass' office at 1225 19th St. NW. Miller, a freelance writer who as a graduate student at American University took a communications law course under Kass, conducts one evening seminars for prospective sellers who want to learn how to do it. The sessions cost $35.

Miller says he explains "how to find out what the mortgage situation is, how to qualify a prospect," and how to pick the best offer among several proffered contracts. The biggest bid isn't always the wisest to chose, he said: The bidder's ability to secure a loan has to be taken into account. "If you accept somebody as a buyer, you're taking your house off the market at great cost."

None of the functions provided by a realtor are particularly difficult, he said, and usually the settlement itself is handled by a lawyer or the settlement company.

"Writing an ad and showing a house don't take special training," he observes. In addition, "People begin to understand there are rather substantial amounts of money in the brokerage commission."

When he was ready to sell his own house last year, he said he "got uncomfortable" when brokers began to describe the services they offered.

"I couldn't identify services I couldn't, with a little effort, duplicate myself," he said.

But in a market where houses are in demand and are selling fast, a seller "still wants to be able to deal intelligently" with buyers "and to know what the alternatives are," Miller added.