The crowd shuffled into the Starlight Ballroom on a recent Saturday night, their heads down, their eyes darting left and right.

They weren't shy. They were checking out each other's sneakers.

"I got these from Australia and I don't think anybody has got these," Sean Hamilton, 31, proudly noted, showing off his silver and blue 2008 Nike Air McFlys. "I've probably got some of the rarest sneakers ever."

The masses were out at the Philadelphia dance club for "Sneaker Pimps," an international six-year-old traveling showcase of unique shoes that attracts both the curious and the collectors - as in people who may have hundreds (like 500) pairs of sneakers on which they've spent thousands of dollars.

Some rotate their collections on their feet. Others keep their footwear pristine in boxes. Still others treat the sneakers as an investment, devoting entire rooms - as well as their relatives' homes - to their collections.

One man showed photos of his bedroom, which included a floor-to-ceiling "headboard" of shoe boxes. Another described his sneaker closets, where the shoes are organized by frequency of wear.

Call them sneaker heads or sneaker freaks, but just recognize they're legitimate collectors.

"Some people collect stamps or postcards. I collect sneakers," said Speedy Uitto, 22, of Gladwyne.

He lives with his parents. His mother, who collects silver jewelry and Tiffany art, understands his passion. His father? "My dad sees it as a waste of money," he said.

This is not a hobby limited to teens and twentysomethings, city dwellers, or people who like certain sports or certain music genres.

Take Hamilton, of Bear, Del., a married, 31-year-old father who works as a graphic artist. He proudly wore a T-shirt that read "Sneaker Nerd," revealed he once spent $1,000 on a pair of limited-edition Spy vs. Spy Pumas on eBay, and described devoting at least one day a month to cleaning the 300-plus pairs of shoes in his walk-in closet.

"My wife is probably going to kill me," he said. "She knows, but she really doesn't know how much they cost." He sees his sneakers as part of his son's inheritance some day.

"They age pretty well," he said.

An underground sneaker culture started in New York City around the '60s and '70s, centered on sports and hip-hop music, said Jesse Chorng, a collector who helped create the course Sneakerology 101 at Carnegie Mellon University in Pittsburgh. But the culture exploded - and became mainstream - in the Michael Jordan era of the '80s and '90s.

"Air Jordans are among the most collected shoes and the first to break the $100 mark," Chorng said. "For a lot of people, they might not have been able to purchase them as kids so now they're older and they want to buy their childhood back."

In 1985, the NBA fined Jordan for wearing his distinct red and black sneakers on the court at a time when the rules demanded only white shoes. People admired his skills and his perceived sense of rebellion and they wanted to be like him. Sales soared. Nike, which had been struggling, got a second wind.

Jordan is long retired, but new editions of his shoes come out each year, and aficionados will tell you they prefer the Jordan 9s (that means ninth in the Jordan line) to the Jordan 11s, or the Jordan 1s to the 13s.

Although rap artists have long praised their shoes in their lyrics, and sneakers have been featured in movies like Do the Right Thing - one character snapped when someone stepped on his brand-new white Air Jordans - even today's shows like HBO's Entourage include sneaker plots. One episode had its main character spend $20,000 on a pair of custom sneakers for a friend.

"For some people, it's about the style aspect, and having something different to wear every day is a joy and a rush," said Nick DePaula, creative director of solecollector.com, a sneaker magazine. He's seen his Web site grow from the thousands of page views at its start in 2003 to two million a month. "Being the first person at school or on the block with a certain shoe is a good feeling. Others appreciate the designer and the aesthetics over the rarity of the shoes."

A collector, DePaula said, is anyone with 20 pairs or more, but more than 50 is pretty standard. He has 350 pairs that fill one bedroom and the basement of his California home.

Some of the most popular designs right now are vintage 1990s, "so you're connecting with the shoes you couldn't have when you were a kid," DePaula said.

Footwear companies know their market: They put out limited-edition designs, leading some collectors to camp out in front of stores days before their release. (In 2005, that led to a pushing and shouting scene - police were called - when about 70 people waited in line outside a New York shop for only 20 pairs of $300 Nike Pigeon Dunks.)

"It's gotten to the point where it's a hyper consumer thing," Chorng said. "People should have a connection with their shoes and know the story of what's on your feet."

Luis Rosario of Hunting Park is proud of his 400-plus-pair collection, which includes numerous originals. He and pal Joe Colon operate www.grantheftshoez.com, which sells rare shoes and T-shirts Rosario has designed.

But Rosario isn't parting with anything in his personal collection. He's proud of his rare shoes, displaying them at Sneaker Pimps and allowing some visitors to pose for photos with a $1,000 pair of sneakers designed by Kanye West.

"A pair comes out today, I'll wear them for a week, and next week, I'll have something else," said Rosario, who manages a sneaker store.

He pointed to the goods on display: sneakers, empty shoe boxes. "That box alone goes for $200," he said, pointing to an early Air Jordan box. An advertising prop from the original Air Jordan line drew continual cash offers of up to $1,000, but Rosario refused to sell.

"It's like owning a piece of history," he said.

Melanie Kelly watched Rosario proudly display his shoes. She's married to Colon and has been a friend since childhood.

"Since we were kids, it's just been his thing," said Kelly, of South Philadelphia. "There are worse habits to have. He doesn't drink. He doesn't smoke. This is what he does."