Miller and Murphy, however, instead built a completely separate and alternative listing service — a parallel market, much like the Nasdaq, which rose in recent decades to challenge the New York Stock Exchange's dominance and sparked competition that eventually reduced transaction costs for all stock investors.

The price competition is startling. FsboMadison listed about 2,000 homes in 2005 and said that about 72 percent of its listings sell. If those 1,440 houses averaged $200,000 per sale, the real estate commissions under the Realtors' 6 percent system would have been about $17.3 million. Miller and Murphy collected about $300,000.

"They don't care — they're not profit-driven," said Francois Ortalo-Magne, an associate professor of real estate at the University of Wisconsin who has studied residential sales in Europe and the United States.

That lack of profit motive — big profits, anyway — may be the reason FsboMadison is succeeding. Most entrepreneurs want to quickly grab a piece of that $60 billion in commissions by offering a price lower than what most real estate agents charge to attract consumers. Miller and Murphy, working patiently, are focused on providing a place for buyers and sellers to meet and exchange information.

"I don't think we've done anything unusual," Murphy said. "We are not out to take over the market, to eliminate the real estate world. We're just here to offer this service."

For hardship cases, divorces mostly, they waive the $150 fee. They refuse to accept referral fees from real estate agents, lawyers or others. Advertising on their Web site costs $150 a year — $250 with a corporate logo. And payment for listings is by personal check only, an anachronism in today's world of immediate credit card transactions, a policy designed to save people from listing their house on a whim. "Some people are impulsive; they're not ready," Murphy said.

In 1997 Murphy and her husband bought a house together and she decided to sell her place without a real estate agent. But it was a hassle. "You'd have to guess. Do we put a $120 ad in the paper this weekend?"

Her husband suggested she start a Web site. At a play date with their 1-year-old daughters, Murphy, a former nurse, bounced the idea off her cousin, Miller, who told her husband about it that night. "We both laughed about Mary Clare's stupid idea," Miller said.