Two teenage boys eye rows upon rows of sneakers, sizing each up for rarity and signs of use. One of the boys points to a pair of limited-edition Nike Yeezys and said he is buying them for a friend.
"How much is he paying for it?" asks the seller, 15-year-old Alex Asfar.
"16," the boy responds.
When they say "16," they mean $1,600.
"16, there you go," Alex said, counting the wad of cash and handing over the shoes.
These kids are called "sneakerheads" -- sneaker-obsessed teens who run an aftermarket boom of limited edition kicks, buying and selling at prices in thousands and all with their own money.
Every sneaker sale is a potential profit and Alex is a master negotiator.
"It keeps getting bigger," he says, thumbing through a stack of bills. "I can't fit it in my wallet anymore."
Another sneakerhead is Brandon Buscanera. At just 12 years old, he made $100 in one day, which he calls "good for one day's work." Now, he says, he has the cash to go buy more sneakers.
"It's a cycle -- buy, sell, trade," Brandon says. "It's kind of a hobby. .. It's more of an addition, for the love of the game."
It all started with Michael Jordan. In the '80s, when Nike convinced us Air Jordans could make us fly, having them on your feet became a status symbol. To some, the shoes were worth whatever price it took -- including murder.
In 1989, one boy was strangled for his pair of Jordans. Another kid was shot. The story hit the front page of "Sports Illustrated."
Since then, the size of the athletic shoe market has more than doubled to $21 billion a year in the United States alone, which is why Alex and his father, John Asfar, can be found leaving their house in Middletown, N.J., at 6 a.m. on a Saturday to drive to a sneaker convention an hour away in New York City. Along the way, they picked up Alex's friend and fellow sneakerhead, Brian.
When they arrive, the Alex and Brian got to work, setting up shop at a table they paid for with some friends. Soon, it was on. The two go into a flurry of negotiation tactics and bargaining, as hundreds of dollars trade hands.
It quickly becomes apparent that Alex knows this game well. He has brought a pair of glow-in-the-dark signature shoes of NBA star Lebron James that he bought for $250 and sells at the convention for $340.
But in this world of sneakerheads, a man who calls him DJ Clark Kent is the president. He owns at least 2,500 pairs, rarely wearing the same shoe twice. A legend among the sneakerheads, Kent says he got into the shoe game three decades ago. Back then, he says, kids wanted the shoes, but today kids want the glory of the sale.
"These kids today don't seem like they want the shoes, they want the thing that goes along with having the shoes," Kent says. "Somebody figured out that there's money for a pair of sneakers because of the hype."
The hype is generated by Nike, which denied "Nightline's" requests to talk about its marketing strategy. The company only makes a limited supply of prized sneakers and so when a new one is released, the frenzy ensues and the price goes up.
In recent years, the demand has gotten out of control. Kids camp out in front of shoe stores waiting to the limited editions. In some cities, riots have broken out.
Nike had to rethink its strategy to quell the violence so they now put their hottest shoes for sale online -- opening sales for the new kicks on Saturday mornings.