Shalinda Williams wanted to set some tongues wagging at the Dorsey High School prom in Los Angeles, but she knew a long slinky dress and rhinestone-studded stilettos wouldn't do the trick. So the cheerleader and honor student, 18, headed to Extensions Plus in Reseda, Calif., armed with $500 and 20 pictures--cut from magazines--of Beyonce Knowles and her internationally famous hair.

"I love the way Beyonce looks so different each time, and it's the hair," says Williams, who purchased eight ounces of 18-inch-long straight hair to have woven onto her own. "I couldn't lose 30 pounds or get a nose job before the prom, but I knew I could add some hair to make me look amazing."

Forget about those new Jimmy Choos or that Marc Jacobs bag. The hottest accessory for all sorts of women this season is hair, lots and lots of it. Why the surge? New techniques and better quality tresses are part of the answer. Throw in Us Weekly regulars like Halle Berry and Tyra Banks flashing flowing locks made of "bought hair," and you've got close to a $1 billion-a-year business, according to the Association of Beauticians in Los Angeles. "I have to say, within the last two years there's been a huge jump in the demand for hair," says Helene Stalh, owner of Extensions Plus, who's been watching trends come and go since Pam Grier sported her blowout Afro.

New methods have made weaves nearly undetectable and therefore no more startling than a highlight job. The old way involved braiding a woman's hair in circular cornrows and sewing locks onto them. Now hair can be glued on piece by piece to the woman's own strands (the infusion method); sewn into a form-fitting net that's placed over the head (net weaving), or glued in large strips directly to the scalp (bonding). Like many trends, hair extensions were initially popularized by African-American women (think Janet Jackson). But stylists dismiss the antiquated notion that black women add long straight hair to their own in an effort to "be white." "That's the one thing that I hope is dying out with the popularity of weaves now," says Angela Stone, of Exclusively Yours in New York. "Wanting to have options with your looks is not about being white. The best part of my job is watching women with low self-esteem and low confidence leave on top of the world when we add the hair. That's priceless." Some of those women who need an, uh, ego boost include recent weave aficionados Britney Spears, Paris Hilton and Jessica Simpson.

Each year 2 million to 3 million pounds of human hair are imported into the United States from places like China, Russia, Indonesia and India for use in weaving and other hair products. As with any high-end product, price depends on quality, availability and export restrictions. That means an ounce of European hair might go for $35, and an ounce of Russian hair with highlights and other chemical processes can fetch $250. A full weave usually requires eight to 12 ounces of hair and can cost from $200 to $6,000.

And you get what you pay for. Bonding, the least expensive method, lasts only about two weeks, and you can't shampoo without having your hair go down the drain. Infusions cost the most and take eight or more hours to complete, but once you're done, you can swim, sauna and pull your hair with abandon for up to four months. Nobody ever said beauty was simple.