Reality's Bites The market for baby-boomer memorabilia is topping out. Is it time to buy into skateboarding, videogames, and '90s rock?

Master of feedback and flaming grand finales, Jimi Hendrix is now rocking the auction house.

In November, an inscribed copy of the 1967 album Axis: Bold as Love by the Jimi Hendrix Experience, his band, went for $20,000-twice its estimate-at Christie's. His Fender Stratocaster guitar brought $168,000 at the same sale. Fellow rocker Eric Clapton's Strat, known as Blackie, still holds the auction record of nearly $1 million, paid in 2004. But many experts believe the Stratocaster that Hendrix wielded at Woodstock would fetch more.

It's not just musical prowess that is driving these prices, nor the intrinsic value of the guitars, originally purchased for a few hundred dollars. As with art, what's considered hot among collectibles shifts with each generation. People tend to collect out of a sense of nostalgia, often for their own youth. And right now, the market reflects the taste of the generation with the most disposable income: baby boomers.

"In the early '80s, baby boomers started getting nostalgic about the Beatles and the Rolling Stones, and that gave birth to the whole market for pop culture," says Simeon Lipman, Christie's popular-culture specialist. Demand for rock-and-roll relics has been growing ever since, along with comic books and sports memorabilia from the '50s and '60s. Comic-book collecting peaked in the late '80s, but early Iron Man comics, from the '60s, still sell for as much as $6,500 on eBay, and baseballs signed by Lou Gehrig or Babe Ruth can go for $7,000.

But appraisers say it's a mistake to assume that what's popular now will stay that way. Generation X is unlikely to have the same fascination with Eric Clapton or muscle cars like the Corvette and Camaro. "When I started collecting records, opera 78s were in big demand. But now, most of those collectors are dead and opera is no longer hot," says Michael Sherman, a collector and appraiser based in Orange County, California. "Baby boomers have the same nostalgia for rock and roll, and we pay a lot for it. Interests shift."

Prices for choice Beatles memorabilia are still astronomical but starting to drop, experts say, while demand-and prices-for items connected to popular '90s bands such as Nirvana and Guns 'N Roses is rising. "A guitar of Kurt Cobain's was worth maybe $10,000 a decade ago," says Lipman. "Today, you couldn't touch one for less than $100,000. You're seeing younger collectors getting to the point where they have a little expendable income and are beginning to long for their glory days. That's what this is all about. It's an organic kind of madness, the collecting thing."

Auction houses have begun looking for ways to attract younger buyers without alienating the boomers who drive their sales. Inspired by the youthful fashion craze for vintage concert T-shirts, Christie's held its first sale of them in November. A Yardbirds T-shirt worn by rock journalist Greg Shaw to the Monterey International Pop Music Festival, in 1967, sold for $3,000, while a pretty ordinary Led Zeppelin T-shirt went for $1,625. "Younger buyers might not even listen to Led Zeppelin," Lipman says, "but they want the T-shirts because they're cool."

Generation X is smaller in numbers but growing in spending power. Its top earners are Web 2.0 entrepreneurs like the founders of Google and YouTube, newly minted law partners, and corporate leaders who grew up in a computerized world. As this group begins to buy back its youth, new trends are surfacing. Skateboarding culture has produced its own niche collecting cult. Especially coveted are mint-condition "decks" from the '80s, when skateboard art got wildly creative along with the sport itself. An original 1984 Phantom recently sold for $7,250.

Where baby boomers are more likely to drop $6,000 on a '50s-era brunette Barbie, Gen X is intrigued by the boys' toys of the '70s and '80s. Star Wars action figures still in their cases bring impressive prices, as do Hasbro's Transformer series. Doll-size robots like Targetmaster Scourge, purchased for a few bucks in 1987, now sell on eBay for $5,000.

It's not too late to get in on Gen-X collecting trends. Unlike boomers, this group is relatively new to frivolous spending. "You have to look at what has really gotten people excited," says Lipman, who is 33. "Unlike kids from the '50s and '60s who would go outside and play ball and pretend they were Mickey Mantle, we would stay home and play Super Mario Brothers. Now people are trying to get their hands on the systems and games. It wouldn't surprise me to see computer memorabilia and even computers themselves take off. Rare ones like the original Macs already go for lots of money."

What will appeal to the millennial generation is anyone's guess, since its members have yet to accrue much disposable income, let alone spend it. But limited-edition items related to Harry Potter are likely to rise in value among the children who waited in line for J. K. Rowling's latest releases. So are trading-card games like Yu-Gi-Oh!, avidly collected by kids in the late '90s. Rare prize cards such as Doomcaliber Knight can fetch a couple thousand dollars on eBay, and the category in general-and related videogames-are likely to appreciate as those kids age.

Of course, not every collection is based on reliving youth. How else can one explain the continued fascination with Marilyn Monroe? Demand for silent-era mementos has faded, and Hollywood classics are losing ground as collectors who came of age in movie palaces give way to those who watch films on iPods. Yet Marilyn endures. "For the last six years, Marilyn Monroe has been our biggest seller at auction," says Margaret Barrett, director of entertainment memorabilia at auction house Bonhams & Butterfields. "She died in 1962, so she's pre-baby boom. Yet she appeals to collectors in their twenties and seventies-male and female. Every generation seems to discover her."