At the end of June, Apptopia founder Jonathan Kay told us the company had just passed $100,000 in sales. Considering they hadn’t even been up and running for three months, the number was a promising one. “We’re the only people on the Internet to do this right now,” Kay said at the time, and it didn’t take long for investors to start taking notice.

Not just any investors, however, but Dallas Mavericks owner Mark Cuban. Apptopia has just announced Cuban’s led a new investment round, investing $500,000 into the company.

In total, the round will be $1 million, which Kay expects to close within the next two to three days. Their total money raised to date will now reach $1.4 million, following Ryan Melohn’s initial investment from Expansion Venture Capital earlier this year.

“This dude is my idol,” Kay says of Cuban. “Both as a sports fan and an entrepreneur.”

Kay met Cuban when he working as Grasshopper’s former Ambassador of Buzz. During that time, Grasshopper launched Chargify, which Cuban also invested an undisclosed amount in. After Kay told Cuban he was building an eBay style marketplace which brokers the sale of apps, Cuban was interested. “And when he found out what our six-month vision is, he said, ‘I’ll put in $500,000 in right now,’” Kay says.

The company’s already grown to eight employees, and they’re beginning to “hire like crazy” both in Boston and San Francisco. Considering app sales on Apptopia have continued to double month over month, it’s clear why they need to bring on a bigger team.

“Five little guys have already cropped up,” Kay says, referring to the competition. The statement’s humorous considering after Kay previously claimed they were the only company on the Internet to tackle this problem, he had admitted, “Which is a cool thing to say, because I probably won’t be able to say that in a few months.”

Kay says he has more buyers than he has apps to sell right now, and that they’re currently in the midst of headhunting some big mobile players. With the quick progress the team’s already made, who knows what kind of announcement they’ll be making in the next three months.