When Evan Margolin launched Salsa Boot Camp to sell instructional video clips online, everyone he knew told him it was a crazy idea. Why would people offer up their credit cards to him - a dance teacher known only to his students in San Francisco - when they could watch thousands of dance videos for free on sites like YouTube?

Yet aspiring salsa dancers have signed up in droves, even as Margolin has raised the monthly subscription price from $9 to $37. Four months after its launch, SalsaBootCamp.com is making $20,000 a month.

Margolin, 36, found his niche a decade ago, when his big brother dragged him to a salsa club. He eventually became a dance teacher, although his main income has come from various Internet marketing jobs. Margolin says he had toyed with the idea of creating a subscription dance site off and on since 2001 but never did it because the technology wasn’t good enough: The video was cumbersome and slow.

Then last summer one of his students began recording the dance class on a camera phone, burning it to a CD, and asking him to post it on a website. “I thought, ‘Damn, maybe the time is right,’” Margolin says.

He currently has 1,000 members and is adding a few every day. The trick now is to keep it up: keep marketing, keep adding content. It’s not a do-nothing path to riches. But if you can land even a few hundred subscribers, you can make some sweet, and profitable, moves.

CNN Money