Miller Cornell shows one of his favorite finds, a pair of Air Jordan 1 Off White’s, circa 1985. The sneakers are available at his pop-up store, Gorilla Kickz, on Hilton Head Island. CHANDLER HUMMELL

These are definitely not your Grandpa’s Keds.

And his pop-up store, Gorilla Kickz, at Fresh Market Shops on Hilton Head where 15-year-old Miller Cornell sells top brand sneakers is definitely not Sears.

It’s a whole new world of shoe culture out there for buyers and sellers of stylish, limited edition and unique sneakers. Nike is a leader in the market, and Miller’s store has plenty of them to sell.

He acquired his inventory in a way unknown to those guys back in the Sears shoe department: Miller – along with thousands of other sneakerheads – enters a sort of lottery on new releases through an app on his phone.

But let’s back up a bit.

Miller lives with his family in Atlanta during the school year, and they spend summers at their home on Hilton Head Island, where his grandparents live full time.

He said he became interested in sneakers, mostly Nike Air Jordans and Yeezys (a shoe collaboration between Adidas and Kanye West), when he was 12.

“I bought a pair of Yeezys back then and still remember how excited I was to have them,” he said. His interest evolved into a passion for the shoes, especially the Jordans in all its many iterations. He was hooked.

“I love the look of sneakers and following the sneaker market,” Miller said. “It’s cool how something will be released at a certain price, then increase in value.”

When he says “released,” he means an online “drop” by Nike or other sellers of popular sneakers. Nike’s app, SNKRS, for instance, releases new shoes on a published schedule, and all followers know the time, date and price of the shoe. At the time of the drop, usually at 10 a.m. on a random day, interested parties can log in and hope they win the draw. If they are selected, they can complete their purchase and “win” the shoe.

“All of my friends were selling the shoes they bought, and making a lot of money,” Miller said. So he decided he should try to do the same.

“I started selling a year ago and it was slow at first with just a couple pairs,” he said. “When I sold one, I’d buy another.”

Then something amazing happened.

“One day, I won two pairs of Off White Air Jordans, and by selling those, that allowed me to add a lot more stock to my inventory,” Miller said.

Off White is not a color; it’s the name of a line of clothing and accessories by the late fashion designer Virgil Abloh, who collaborated with Nike to create a line of sneakers. Off White Jordans are among the most expensive sneakers on the market.

With that success, and more inventory, Miller started selling on eBay and on Instagram. Last October, he and some friends got a booth at Sneaker Con in Atlanta.

“I sold 44 pairs that day and loved it,” he said. “I then started doing monthly local conventions in Atlanta where I sell 100 to 200 pairs on a Sunday each time – and I also still sell through Instagram.”

The conventions were more work than the young man could handle, so his parents, Dan and Dominique Cornell, stepped in to help. Soon his grandparents joined in.

“A year ago, I didn’t know anything about this,” said Dominique. “Now I have a whole new appreciation for these shoes. I know the lingo, the styles – and it has been fun.”

After the success of the sneaker conventions, Miller set his sights higher.

“I’ve dreamed about having a store one day, then thought maybe it could really happen,” he said. “Since I spend my summers on Hilton Head, I wanted to try something new with renting space and having a pop-up store front.”

Thus was born the Gorilla Kickz store on the island. The family secured an eight-week lease and helped him outfit the store. He has been open since July 1 on Tuesday through Sunday, from 11 a.m. to 7 p.m.

Miller’s mom and grandmother, whom he and all his friends call “Gaga,” help out at the store. On a recent Saturday, Gaga was fitting shoes on one customer and finding a pair of Jordans for another. She is also the go-to for sneaker cleaning. “The secret is a toothbrush and Dawn dish detergent – but not on the leather,” said Gaga, aka Cynthia Hartley-Leonard.

Miller keeps the inventory fresh by entering the drop draws frequently. One recent acquisition is a particular source of pride – and potential revenue. A pair of Air Jordan 1 Off White’s, circa 1985, with the “Carolina Blue” colorway of Michael Jordan’s alma mater, the University of North Carolina, sits on a pedestal in the office. The price? $2,450.

But most of the sneakers are far less expensive. Miller said his average price for Nikes is about $175.

He also buys shoes from customers, after checking the shoes with a blacklight to see if they are authentic, or have been worn. On that Saturday, a young man brought in a pair of Nike Dunk Low Panda Reverse shoes. Miller bought them for $120 and said he will likely sell them for $150. “I just want people to enjoy the experience,” he said.

But the fun is ending soon – at least for this season. Miller said they will close the store Aug. 7, because he has to go back to school in Atlanta.

“It’s been so great. I love seeing how happy people are when they come in the door,” Miller said. “I’ve met so many nice people. I’m grateful for all the support locals and tourists have given me by coming into the store. It has been the best experience and I hope to be back next summer.”

Though the brick and mortar is closing for now, customers can still always find the coolest sneaks on Instagram