Real estate developers are reviving the art of the auction to motivate buyers in a sluggish market. Developers of residential or office condominiums are using the auctions to speed sales in a slow market. In March, Accelerated Marketing Partners auctioned off condos in the high-rise Solaire in Orlando, Florida. The auction set the market price, an equity partner said, and the developer has been selling more condos at a higher price. Auctions are less popular in New York’s resilient market. Louise Sunshine, chairman of Sundezio, said she’d had success with the method, but said that auctions often have a “distressed” connotation and can scare buyers away.