Since the mid-1970s, Prince has collected literature and related memorabilia, including one of two inscribed copies of James Joyce’s Ulysses known to be in private hands, as well as the pulp novels and advertising illustrations that have made their way into his own art—results of a kind of hunting and gathering that he describes as “beachcombing.” But the artist has also built up notable holdings of postwar paintings. “I have one of the ‘retrospective’ Warhols, which I just lent to a show at Gagosian this summer, and I have a ‘Car Crash,’ ” he says. “I have a really nice flower painting, too.”

Prince acquires some of his pieces by trading with other artists, including Damien Hirst. Hirst and Prince also exchange their works with Gagosian, who represents them both, for other high-value property in the dealer’s substantial inventory of secondary-market material. For all concerned, the transactional relationship is a match made in art-buying heaven, enabling them to take advantage of section 1031 of the tax code. Under this “like-kind exchanges” provision, the owner of a Warhol, say, can trade it to another “investor” for a similarly valued Koons while deferring the recognition of any capital gains or losses generated until the Koons is cashed in. At that point, his or her cost basis is calculated by adding the gain to or subtracting the loss from the original purchase price of the Warhol. In the process, both parties in the swap avoid the 28 percent tax that is levied on gains from outright sales, at auction or otherwise, of appreciated artworks.

Prince also purchases artworks from other New York dealers. “Jeannie Greenberg found me a great David Hammons,” he says. “I recently bought a Carroll Dunham and a Christopher Wool from Skarstedt Gallery.” Observes Per Skarstedt, who sells to Hirst too: “Artists don’t buy as an investment the same way as a lot of other people do. They are in it for the long term. These artists make a ton of money, but they have no idea about other types of investments. Art is what they know.”

And they can be quite devoted to certain artists. Hirst, for instance, has a particular passion for Francis Bacon. “I’ve got five paintings by Bacon,” he says. “I always loved him. When I was an art student he was hanging around, and I saw him a few times. I just think he’s one of the world’s greatest painters.” At Sotheby’s New York in November 2007, Hirst, bidding through his business agent, Frank Dunphy, beat out three others for a small Bacon Self Portrait from 1969, paying a massive $33 million—at the time, the fourth highest price for a Bacon at auction. Hirst also possesses the rarely exhibited Untitled (Half-Length Figure in Sea), circa 1953–54, which he acquired from the artist’s estate.

“In the Darkest Hour There May Be Light,” an exhibition of Hirst’s collection staged at the Serpentine Gallery, in London, in 2006, included works by Banksy, John Currin and Warhol, among others, demonstrating the breadth of the artist’s taste. The London private dealer Ivor Braka, known to aid Hirst in secondary-market transactions, describes the Serpentine roster as just “the tip of the iceberg” of the artist’s holdings. Hirst also owns pieces by his Young British Artists peers, as well as many by Ashley Bickerton, says the London dealer Gerard Faggionato. Last February at Sotheby’s London, Hirst bought Koons’s stainless-steel sculpture Kiepenkerl, 1987, for £3.2 million ($6.3 million).

One notable aspect of Hirst’s collecting, Braka says, is that it clearly echoes “his own artistic interests and his own psychology.” Indeed, however genuine Hirst’s connection to Bacon’s art is (he has reportedly painted figurative works, without assistants, in the style of Bacon), it’s not surprising that this one-man publicity machine, who briefly held the title of most expensive living artist at auction, would have a stake in the market for the work of the most expensive postwar artist. Sources close to Hirst say he wanted to make enough from his Beautiful Inside My Head Forever sale in London this past September to be able to afford a Bacon triptych.