It was never the intention to become a millionaire. Michele Venton had moved to Bournemouth from London, hoping to get away from corporate life, and had decided to try selling dresses online.

She found a factory to make her wrap dresses and listed them for sale on Amazon, where she was blown away by the response. Clothes, on the other hand, were not the easiest product to sell online – too many size issues, too many returns.

But, as a mother of two, she had had the awkward feeling of realizing that her children were going to a birthday party in a few days and that she had no present to give.

On Amazon, she began selling emergency gifts for parents. In less than four years, she was doing nearly £10 million in business each year across Europe and the United States.

So, in 2019, when an offer to buy the entirety of her business – for tens of millions of dollars – came her way, she accepted. Amazon allows other sellers to list their wares on its website, and it will even handle delivery or “fulfillment” for them via its formidable logistics network.

Because of Amazon’s massive size, small sellers can quickly sell large sums of money if they get the products and marketing right. With many shops forced to close due to the pandemic, many have seen their sales increase to the point where they are unable to meet all of their orders. When Ms Venton sold her company two years ago, it was unusual to sell a company based solely on Amazon sales. The buyer, a private individual, insists on anonymity in order to avoid attracting competitors or saboteurs – such is the hypercompetitive world of e-commerce.

However, in the last year, a new generation of companies has emerged to provide Amazon entrepreneurs like Ms Venton with a way to sell their businesses.

Thrasio, named after an Amazon warrior in Greek mythology, is the largest and most well-known. They are purchasing one to three businesses per week, with approximately ten in the UK and an appetite for more.

According to its founder, Josh Silberstein, it grew from nothing to more than $500 million (£360 million) in revenue in its second year.

In general, they look for sellers who have managed to rise above the tidal wave of items for sale on Amazon, amassing a large number of positive customer reviews and appearing on the first page or two of results for user searches.

The best Amazon sellers are appealing investments because they frequently have higher profit margins than their offline competitors while still selling for less. The buyout firms hope that by bringing the professional skills and resources of a larger company, they will be able to help the brands grow faster and more profitably.

Amazon buyout firms, such as Heroes, founded by two identical twins, Riccardo and Alessio Bruni, have also sprung up in the UK.

Davaon, a garden tool brand founded by David Stephen, was one of their acquisitions. He was looking for a job that would allow him to spend more time with his family after many years as a traveling salesman, spending long hours in traffic and lonely hotel rooms. He had a business, a brand, Davaon, and $10,000 worth of secateurs in his garden shed after many hours of trawling through the Chinese website Alibaba to find a supplier. Loppers, shears, and garden saws soon joined the lineup, and by 2020, he and his wife were selling more than £2 million a year, purchased from Taiwanese suppliers they had yet to meet in person.

But the goal of a better life remained as elusive as ever. “It got to the point where we were looking at 12 to 15 hours of work per day.” I was working nonstop on weekends. Last year, he began to receive offers for his company. He initially mistook them for rival sellers looking for information.

Despite earning enough to retire on, the thrill of building brands online makes it difficult for entrepreneurs to step away. Mr Stephen intends to launch a new business soon, and Ms Venton has already launched a new Amazon business. It sells “homewares,” but she won’t say anything else for fear of being copied.