SidelineSwap, a startup that’s created an online marketplace where athletes can buy and sell used sporting gear, recently raised $1.5 million in seed funding. The round included investments from 500 Startups, Fabrice Grinda, Maria Thomas (former CEO at Etsy), Sean Bratches (former executive vice president at ESPN), Fullstack Sports Ventures and Summit Partners’ Christopher Dean.

Brendan Candon, co-founder and CEO of SidelineSwap, told us the funding will be used to bring the company’s product development completely in-house, as it prepares to release its iOS app within the next few months. The company will also be using the capital to market to athletes in target sports: lacrosse, hockey, skiing, baseball, softball and golf.

Costs associated with playing sports – from travel expenses to registration fees – continue to rise. And athletes who buy brand spanking new equipment can find themselves shelling out hundreds, even thousands of dollars. In contrast, Candon said the average sale price on SidelineSwap is $80.

“Those costs are only going up,” Candon said. “We’re addressing one piece of the puzzle by making the equipment more affordable.”

The fate of Sports Authority and City Sports, both of which filed for bankruptcy in the past year, suggest brick and mortar sporting stores are struggling as ecommerce becomes more popular among consumers. That’s why SidelineSwap is banking on the growing peer-to-peer trend as it builds an online marketplace for sporting goods.

Candon pointed to other marketplaces that have “verticalized eBay,” like Etsy, which has rallied artisans and craft-lovers to come together in a single place online. He said, “It’s the same with sports. Athletes love their gear, they want a sports-specific experience and we can build a community around that.”

SidelineSwap takes a 12-percent cut on each transaction from sellers. And because the transactions are peer-to-peer and deal with used sporting equipment, the company has built buyer protection into the marketplace, holding any money exchanged for a certain period of time before clearing the transaction.

While 80 percent of its users are under the age of 22, SidelineSwap is attracting an unexpected demographic that has also made it a memorabilia marketplace of sorts. “One of the big sellers in Boston is a former Harvard hockey player… who sold all of his gear after he graduated,” Candon told us. “We’re starting to have a network of college athletes. After school, they become just like everybody else and could use the money.”

Although SidelineSwap has technically been based in New York, it has strong ties to the Boston area. The venture was a MassChallenge finalist in 2015, in addition to working out of the Harvard iLab this past spring. Currently, Candon said 60 percent of the team is in Boston, with the remaining members planning to move up to the Hub this coming year.