Developer Harry Macklowe could reportedly sell the General Motors Building this month to pay off debts with Deutsche Bank. Bids for the 50-story building are due Feb. 15. Macklowe made his stake in the building collateral for a $1.2 billion bridge loan by Fortress Investment Group, which financed the $7 billion acquisition of seven Manhattan office buildings last year. The cost of borrowing has shot up by one-third since Macklowe bought the buildings, said Scott Singer, executive vice president of New York-based Singer & Bassuk Organization. While some say Macklowe paid too much for them, Howard Michaels, chairman of New York-based Carlton Advisory Services Inc., said Macklowe “paid an appropriate price at the time he bought the properties. It was a major score for him. And it was unforeseeable by him or anybody else that the market would change so drastically.”