28-year-old's company makes millions buying from Walmart and selling on Amazon

As a student at Winona State University, he organized textbook buyback events on campus twice a year. He listed the books on Amazon and shipped them out to customers around the country for a profit of up to $10,000 a year.

The process worked simply enough: Using the Amazon Seller app he could see exactly how much he could expect to profit on each book and in what time frame. But the hours spent processing and packaging each order himself proved to be a bit much.

"Going through that process for one semester was enough to know that I didn't want to do it again," he says. "From there forward I did Fulfillment by Amazon the rest of the way."

Using Amazon's fulfillment services meant he could ship all the books in bulk using preferred UPS rates to an Amazon warehouse, where, for a fee, the online retailer handled processing and shipping out each individual order. It made his side hustle more manageable, time-wise.

And, when Grant grew more unfulfilled at his accounting job, it sparked the idea of going online to flip more than just textbooks.

After work and on the weekends, he scoped out the clearance aisles at Walmart, scanned a few items using Amazon's app and bought up toys, games, and home improvement items he realized he could re-sell for a profit. A receipt from his early days shows a variety of purchases, everything from vacuums to Barbies, LEGO sets to stainless steel flatware.

"I was putting in about 10 hours per week and I was making in the ballpark of $1,000 per month," he recalls. Once he was able to make the same kind of money reselling on Amazon as he had made at his accounting job, in September 2013, he quit.

"I was confident that if I had full-time hours to dedicate to selling online that I would be able to more or less scale that up," Grant says. Just three months later, in December, he notched $9,000 in profit on over $25,000 in total sales.

"Making that amount of money in one month was a big boost in my confidence to be able to scale up further from there," he says.

Boxes upon boxes destined for Amazon warehouses started stacking up in Grant's duplex so, in the spring of 2014, he rented out a 725-foot warehouse. He packed his Mazda 626 full of products on runs back and forth from other brand-name retailers like Target and Toys R Us.

"It was starting to basically take over my life because I'm coming home and there's product all over my house," he recalls. When the 30 hours of shopping and the 15 hours of preparing shipments each week became too much to handle alone, Grant hired his first employee, a friend who could help scour local stores.

Eventually it got easier to target the items that had the biggest opportunity for arbitrage. Seasonality, they realized, was a key factor. They could, for example, buy up discounted candy after Halloween and half-priced Christmas decorations around the New Year.

"Believe it or not, there's actually people buying those items out of season," Grant laughs. Still, even he was surprised at how quickly the business took off from there.

"I went from just me in this business doing around three-to-five thousand dollars in sales per month and now, four years later, we're a team of 11 and we're doing well over $200,000 in sales per month," Grant says. The team had to move to a warehouse that's over five times as large as their first this past July.

Since he started selling on Amazon, Grant says the business is on track to top $8 million in total sales by the end of this year. Profits are heavily reinvested back into the company, though Grant was still able to take a salary of around $150,000 when he was working for the venture full time.

The team also made mistakes made along the way. They lost $6,000 when a faulty nail filing product for dogs got Grant's Amazon seller account temporarily suspended, for example. They also had to pay the fees Amazon charges for products that failed to sell and sat idly in Amazon's warehouses.

All the same, Grant believes he has found an easy and effective formula for success. "I think anyone can do it if they're willing to put in the work," he says.

As his business is increasingly run by his team, Grant has reduced his salary down to $60,000 a year and now dedicates much of his time to getting that message out. He consults and teaches e-commerce classes through the same blog he has been using to track his performance. His hope is that he might be able to help a few people who might not be happy at their jobs find the same independence he did.

"I was just looking to have freedom of schedule and replace the income that I had from that job and now it's turned into a lot more than that," he says. "I mean, I would be sitting in an office cubicle now or working at a client location as opposed to doing what I want to do effectively when I want to do it."