In 2004, the couple opened the Rubin Museum of Art (RMA), a 70,000-square-foot showplace in Manhattan’s Chelsea neighborhood. The RMA, the first and only museum in the Western world dedicated to Himalayan art, has won rave reviews. Art critic Holland Carter, writing in The New York Times, paid the Rubins what is perhaps the ultimate compliment: "There is no question about the seriousness of its scholarly intentions."

While "vanity" museums, stuffed full of second-rate or unintelligible collections, are widespread, the number of those who invest the time and effort to establish serious institutions is growing. Wal-Mart heiress Alice Walton plans to open a 100,000-square-foot museum called Crystal Bridges near Wal-Mart’s headquarters in Bentonville, Ark., in 2009. Elton John will display his 20th-century art assemblage to the public in an extension to his Windsor home.

"Art should be seen, and not buried in bubble wrap. That’s what would have happened to our collection if we had donated it to a museum."

Collectors who decide to launch a museum are often surprised at the effort required. Shelley Rubin says that founding the RMA turned into a full-time job, one that they took on just when she, 63, and her husband, 71, were considering retirement. "We had never done anything with a museum other than walk in, look at the art and leave," she says.

But they were motivated by the fear that if they donated their collection to an existing organization, it would be hidden away in storage. "Art should be seen, and not buried in bubble wrap," Don Rubin says. "That’s what would have happened to our collection if we had donated it to a museum." Picking a less-expensive city for their institution never crossed their minds, in part because their collection is so unique that it might have had a difficult time finding an audience outside a cultural Mecca such as New York.

Ed Able, president of the American Association of Museums, a group that represents 17,000 large and small museums, zoos, botanical gardens and aquariums nationwide, says many people call his organization to inquire how to start their own institution, but only a very small fraction follow through. "Once most people start to investigate the true costs of starting and operating their own museum, they realize that it’s enormously more complex than most people know," he says. He has found that the biggest surprise for most collectors is that the general public is often unwilling to support a privately funded museum, either with donations or membership or even individual admission and gift shop purchases. Many visitors believe that if you are wealthy enough to start your own museum, you are wealthy enough to keep it going with or without support from the local community.

However, collectors and their heirs often feel that a museum has no business being in business, especially for the long term, if it does not enjoy a steady stream of enthusiastic visitors. For that, an institution needs to offer the public an experience that sheds new light on its understanding of art, not just a glimpse of a collection—even if it is among the best of its kind.