When a pair of Florida developers in 2006 acquired a 19th-century stable and carriage house in SoHo, they celebrated with great fanfare, even hosting a week-long art exhibit featuring the graffiti that covered the facade and inside walls.

The developers, Caroline Cummings and William Elias, spent $12 million to buy the building at 11 Spring St., which had long been vacant, from a former publisher of the New York Post, Lachlan Murdoch. They then invested $10 million to convert it into three high-end apartments, the costliest being a $17.95 million triplex penthouse with a private elevator.

Now, after nearly nine months on the market, the developers have yet to sell anything.

“Of course they haven’t sold,” the broker who represented Mr. Murdoch, Larry Michaels, said. “Even if you retrofit it with the biggest bling, it’s still a five-story brownstone in Little Italy. … They aren’t going to sell at those crazy prices.”

Mr. Murdoch originally bought the building for $5.25 million in 2003, he said.

In addition to the penthouse, there is a three-bedroom apartment for $15.15 million and a two-bedroom apartment listed at $6.7 million. The average price a square foot is more than $3,500, compared with the average price of $2,223 a square foot for luxury buildings in Manhattan and the average price of $1,450 a square foot in SoHo and TriBeCa, according to fourth-quarter market data from the appraisal firm Miller Samuel.

“They will have to either reduce prices by 30% or leave it on the market until the economy swings back up,” Mr. Michaels said. “This is a very educated marketplace.” The listing broker at the Corcoran Group for the apartments, Robert Browne, said they haven’t sold because construction on the building is not done. “Nobody can go inside and see how fantastic they will be,” he said, adding that construction is set to finish in June.

While buying an apartment in the pre-construction stage is not unusual, this building does not offer a model apartment simulating what the units will look like, making a sale more difficult, a broker specializing in luxury sales, Leonard Steinberg, said.

He added that it may also be a result of bad timing. “It’s a very high price for that area,” he said. “A year or two ago, though, it would have gone right off the market. Things were crazy and people thought if they took their time, they’d lose it.”

The SoHo building, which is at the corner of Spring and Elizabeth streets, was once known as the Candle Building, but over the last several decades it has become an unofficial canvas for street artists. The walls inside and the first floor façade are covered in graffiti and other paintings.

Mr. Murdoch originally planned to make the entire building his private residence, but after falling out with his father over the future of their news empire, he returned with his wife to Australia.

After buying the building, the developers invited street artists to paint their last works on the walls, and the space was opened for a short period to the public.