Flash sales have been used to sell clothes, vacations and even cars—now they are being used to sell spots on wax. Now through Friday, August 26 at 4:00 p.m. PT, Macy Gray is offering fans the opportunity to purchase a slot as a backup singer on her next album. Visitors to the Los Angeles edition of GiltCity.com this week were greeted with the $1,350 prize, which secures a spot on the chorus on a song, lunch with Gray, their name in the liner notes and a signed copy of the completed project. Those who purchase the offering will record at the Los Angeles studio on September 4. Check it out here.