Songstress Mariah Carey must be survivng the economic downturn because the ‘Heartbreaker’ singer has put a bid on the world’s most expensive house. The property, which is located next door to Hugh Hefner’s Playboy oansion in Holmby Hills, California, is said to be worth $246 million and boasts 15 bedrooms with marble and gold embossed leather walls, a library containing rare books, two kitchens, a screening room for 50 and staff quarters for 10.