People in the 18th and 19th centuries collected hair as a keepsake to remind them of loved ones, much as religious people have long kept skull and bone fragments as holy relics. In the world of collecting, what's old is new again: Hair, clothes and other ephemera belonging to celebrities are hot.

“It's an old hobby that is making a comeback, and collectors are taking it very seriously,” observes Adrian Roose, a specialist with the London-based auction house Paul Fraser Collectibles. “A one-inch strand of Elvis Presley's hair will typically sell for $1,600 at auction. The most expensive hair was a clump from the head of Che Guevara—that sold for more than $100,000 a few years back.”

Clothes worn by celebrities can be just as expensive. On the auction block at Paul Fraser in mid-November, for instance, was a black turtleneck worn by Andy Warhol (asking price roughly $15,800), while a floral dress worn by Marilyn Monroe in the 1962 film “Something's Gotta Give” sold for $57,600 on eBay, making it one of the auction site's priciest items in 2010. Marked-up film scripts and handwritten song lyrics are also popular, as well as sports trophies and uniforms owned by famous athletes.