The Idaho Statesman reports on where the speculators went. "For the first time, the average sale price of Ada County houses is more than a quarter-million dollars, real-estate industry data show. You can thank, or blame, job growth and Californians."

"Yet the boom contains the seeds of a slowdown, real-estate executives say. They say high prices and rising vacancy rates among rental homes are scaring off some investors, while rising interest rates and the increasing difficulty Californians have selling their homes could slow the pace of residential purchases."

"The average sale price of a home in Ada County reached up 24 percent from the same quarter in 2005. 4,114 new and existing homes sold in Ada and Canyon counties during the first quarter, a 39 percent increase over the same period a year ago."

"One-fifth of all home loans in the first nine months of 2005 went to investors, according to LoanPerformance. One such investor is Rob Rose, who calls himself a genuine residential real-estate investor, not a speculator who goes into a market with the idea of flipping a property for a quick profit."

"'What I found was that Idaho was an undiscovered treasure,' said Rose, who owns seven investment rental properties in the Boise area."

"But Tony Drost, owner of a Boise-based firm that handles single-family rentals for investors, said clouds may be forming. Drost said a quarterly survey of 1,237 investor-owned single-family rental homes managed by 51 local property managers found that 11 percent of the units are vacant."

"The immediate concern is that the owners, having concluded that the Idaho market is slowing, will begin selling hundreds of single-family homes at reduced prices, driving down home values."

"Rose, the California investor, agrees the investor market is beginning to cool. 'Most of the money going into Idaho is from California,' he says. 'But the California market is slowing big time. People are having a hard time selling, so the investment money going into Idaho is going to slow.'"

"J.J. Suitter, who manages some of Rose's properties, said price and the number of homes on the market is becoming a factor for investors. 'Some are losing interest because prices have gone up so much,' she said. 'Some are seeing their rentals sit empty for as many as four months.'"

"Suitter said the survey covered only rentals handled by association members and may not truly indicate market conditions. 'There are thousands of them (investment properties) out there, and nobody really knows how many are sitting empty.'"