REX Real Estate Exchange, which charges a selling commission of 2 percent instead of the usual 5 percent to 6 percent, launched its Long Island operation last week, when it started operating out of a co-working space at RXR Plaza in Uniondale. The Los Angeles-based company expects to start listing New York-area homes on its website, rexchange.com, later this week.

Traditional real estate fees "are just crazy high compared with every other industry in the United States," said Jack Ryan, Rex's chief executive and a former partner at Goldman Sachs. Decades ago, investment brokerages charged 12 cents a share for stock trades, but now they charge less than a penny, he said. By lowering real estate fees, he said, his company is "doing the same thing with residential real estate."

REX, which has raised $16 million from investors, is not the only company seeking to upend the residential real estate sales model.