Buying stuff at Walmart and selling it on Amazon nets this guy millions of dollars

There may be untapped millions to be made in the clearance racks of your local Walmart.

That’s according to a 28-year-old former accountant who told CNBC that he makes six figures raiding the big-box store’s discount aisles and flipping the items on Amazon.

Ryan Grant told the site he simply browses the store, smartphone in hand, comparing the price tags to those listed in the Amazon Seller app to gauge potential profits. He then uses Amazon’s fulfillment service to ship items in bulk at cheaper rates afforded by the online shopping giant.

Grant, who lives in Minneapolis, first perfected this system selling textbooks in college. But it wasn’t until he quit his accounting job four years ago that he really ramped up the operation, eventually renting out a 725-square-foot warehouse to store the boxes upon boxes of products.

"Pretty early on I realized I wasn't in the career path that I wanted to be on," he told CNBC. "That experience really had me looking for other options and I was starting to explore ways that I could basically leave that job and have my own schedule and be on my own time."

From there, he started hiring employees and calculating the finer points of the resale strategy—a big moneymaker is holiday fare bought for cheap immediately after the day and then sold the next year, Grant told the site.

He claims his business is on track to pull in $8 million by the end of this year, though most of the money will be reinvested back into the operations. His own salary now only comes out to $60,000 per year from the business.

Walmart has been doubling down on efforts to challenge Amazon’s dominance of American e-commerce in recent months with its network of hundreds of stores playing a central role. But there’s clearly still enough of a difference between the two business models to make for some major arbitrage opportunities.

Grant also teaches e-commerce classes, blogs about selling strategy, and does consulting work.