The new Versace campaign, completed in two days and shot by the fashion photographer Mario Testino, cost around $500,000 to produce, the company says. (For Versace, that actually exceeded the cost of some of its recent campaigns featuring Madonna, Moore, Halle Berry and other "friends of the house," who posed for nominal fees, free clothes or charitable contributions.)

Models can also be easier to work with, says Ivan Bart, senior vice president of IMG Models, which represents actresses and models such as Carolyn Murphy, Moss and Shalom Harlow. "They're professionally trained to be photographed incredibly well," he says. "They know which camera angles work."