The sofa as a status object is not a new phenomenon, but what qualifies as one has evolved well beyond the typical large, expensive, and room-commanding pieces found at many design showrooms. Now a different kind of sofa mar- ket has developed: one for ultraexclusive limited-edition pieces by world-class designers, created more like works of art and sold by high-end furniture galleries that are betting these sofas will someday command returns as staggering as Royère’s Polar Bear (sold at auction last fall for $497,000).