The redefinition of architecture as art is continuing in the marketplace. Over the past few years, Pierre Koenig’s 1958 Case Study House # 21 sold at Wright Auctions for $3.2 million; Mies Van Der Rohe’s 1951 Farnsworth House went for $7.5 million through Sotheby’s. Can Richard Neutra’s Kaufmann House in Palm Springs fetch $15 to $25 million? Christie’s bets that the fully restored gem of modernism can compete with the record-breaking prices being paid for modern and contemporary art. Like a $25-million David Smith sculpture, it’s from a similar period, and also made of metal. And you can live in the house.