Cai Guo-Qiang specified that the T-shirts, scarves and tote bags accompanying his “I Want to Believe” show, which opened at the Guggenheim last February, have actual holes in the material to mimic the effect of the explosions used to produce his gunpowder drawings. He created a pattern that was burned into the fabric by hand using incense sticks, says Katherine Lock, a retail buyer at the museum.

Of course, there’s no telling how Lorenzo Ghiberti would have felt about seeing the angels in his Gates of Paradise gilded-bronze panels transformed into Christmas tree ornaments, or what Frida Kahlo, a stalwart Communist, would have thought about her self-portraits being reproduced not just on T- shirts but on coffee mugs and luggage tags. Today, however, many artists are more than amenable. Contemporary stars as diverse as Richard Prince and Kiki Smith have become masters at commodifying their output. Few, though, have gone as far as Damien Hirst and Takashi Murakami, who have transformed themselves into must-have brands: the former with his planned London store Other Criteria, selling such items as T-shirts, postcards and a £25,000 gold charm bracelet, derived from his work, and the latter with a product line ranging from key chains and soccer balls to erotic videotapes and Paint Your Own Ms Ko2 model kits. “For Takashi, the ownership of this identity, of this imagery and iconography, is more important than the objects themselves,” says L.A. MoCA’s Schimmel.

Given such trends, it should come as no surprise that museums have become more ambitious in the ways they transform the imagery of masterpieces into merchandise. “There’s definitely a marketing component,” says Gail Harrity, the chief operating officer of the Philadelphia Museum of Art, where sales of general merchandise account for 5 to 10 percent of the institution’s overall income. “There’s excitement around buying a catalogue or a memento like an apron that reminds people when they cook at home of their wonderful visit to the museum.” As in other areas of retail, how people transport their purchases presents a huge advertising opportunity. Says Gerstein: “We invest in very expensive shopping bags with a major image from the exhibition. People keep them and even bring them on planes.”

No longer, then, is art just for art’s sake—or for the sake of a few choice collectors, for that matter. From its modest roots in the museum shop, artist merchandise has exploded onto the art scene, to the pleasure of some and the dismay of others. The pleasure seems to have prevailed. This summer at the ©Murakami store in the Brooklyn Museum, one young man bought a Kaikai doll for his girlfriend, while a 30-something couple from Paris toting a giant, smiling pink-and-white flower cushion said they would have preferred the supersize version but couldn’t figure out how to get it home. The store clerk says the Murakami-designed shopping bags—essentially free souvenirs with a minimum purchase—were so popular that customers literally fought over them.

Also this summer, in the shop located beyond the fabulous couture dresses and costumes of the Met’s blockbuster “Superheroes: Fashion and Fantasy” exhibition, two friends discussed the merits of stringy Spider Web Shawls, while teenage boys exchanged X-Men and Spidey factoids over pop-up books. Manning the register was Daniel Loor, who channeled Clark Kent by combing back his gelled dark hair, donning thick blackframed glasses and opening his white shirt at the chest to expose the Superman logo emblazoned on another shirt underneath. “This is by far the funnest shop I’ve ever worked in,” he said as he rang up sales among the giddy young crowd. "The Other Art Market" originally appeared in the November 2008 issue of Art+Auction. For a complete list of articles from this issue available on ARTINFO, see Art+Auction's November 2008 Table of Contents.