If you bought your Christmas presents on Amazon this year, there is a decent chance someone in south Florida was taking your money.

Consider the case of Canon color camera filters.

Drive down Northwest 72nd Avenue in Doral, Fla., and you are unlikely to find anything remarkable about the many corrugated metal storefronts lining the road.

But enter through the side door behind the shop emblazoned with a Canon logo, and you will find something unexpected: An ultramodern office with a multi-screen command center straight from the Starship Enterprise.

The set up belongs to GOJA. Over the past decade, founder Walter Gonzalez Jr., a Miami native, and GOJA'S approximately 100 employees have used Amazon's platform to create their own multimillion-dollar e-commerce company. The company declined to state its exact figure but said it was between $50 and $100 million annually, putting it among the top-37 third-party Amazon sellers in the world, according to Marketplace Pulse, a website that tracks Amazon sales and sellers.

"Most people just press 'buy' on Amazon and it appears at their door," said Gonzalez. "But there's a whole world that made it appear at their door. It's like the Wizard of Oz."

Today, GOJA is one of the largest third-party Amazon sellers in the world, bringing in eight-figure revenue moving camera parts, backpacks, batteries and cleaning supplies.

The company serves as an ultrasophisticated example of a booming source of income for an increasing number of south Floridians: selling stuff on Amazon. The area is home to the largest number of Amazon reseller Meetup groups in the U.S., with 1,667 members and counting.

These are not Etsy sellers; there is no homemade knitting going on. Instead, these third-party sellers use data from Amazon to find bestselling products, scour wholesale stores to find cheaper versions of them, then set up online stores on Amazon to sell the items at a profit.

Third-party sellers account for $175 billion in sales worldwide annually, according to Marketplace Pulse, which is double Amazon's own retail. EBay, Walmart and China-based Alibaba also offer third-party opportunities, but none touches Amazon's traffic.

Few if any of these individual south Florida sellers can match the breadth and scope of GOJA. But the sheer numbers of sellers here is telling; according to Amazon, Florida is home to 75,000 third-party sellers, many of them concentrated in south Florida. With few large employers, the region's residents are aces at the entrepreneurial hustle. "It's micro-entrepreneurship," said Bob Hacker, director of StartUp FIU.

Hacker and Gonzalez are partnering to teach classes to high school and college students about the concept. "It makes it easier for someone without a lot of capital to start a business, something that makes it attractive for communities more challenged economically."

His father had emigrated from Bolivia to Miami to take a job as a bank executive, and Gonzalez said he inherited a similar nose for new business opportunities.

The younger Gonzalez gained his first experience with e-commerce at the age of 35. It was 2009, and Amazon was still mostly known for selling books.

"EBay was it," he said. "EBay and your own website."

After successfully offloading a batch of electronics on the auction site, Gonzalez saw an opportunity: If he could sell computer parts, why could he not sell other items? Soon, he was buying toys, handmade funeral urns, and even prostate medicine from wholesalers and flipping them on eBay for a profit.

Gonzalez also decided he wanted to build a trusted e-commerce brand. He hired developers in Bolivia to create software that would pump ads out to eBay users to increase his company's visibility. He called the company GOJA, a riff on his last name.

"GOJA'S plan was always to create a fully integrated e-commerce company that could also serve as the backbone for other companies trying to sell on marketplaces like Amazon," Gonzalez said.