LOS ANGELES — If ever there were a Cinderella of tech, Sophia Amoruso might be it.

In 2006, Ms. Amoruso was a 22-year-old community college dropout, living in her step-aunt’s cottage, working at an art school checking student IDs for $13 an hour. Then she started a side project, Nasty Gal, an eBay page that sold vintage women’s clothing.

Last year, Nasty Gal sold nearly $100 million of clothing and accessories — profitably.

For the last seven years, Ms. Amoruso has been courting a cult following of 20-something women. Nasty Gal has more than half a million followers on Facebook and more than 600,000 on Instagram. But it is not yet well known beyond that base. At fashion trade shows, the company’s name still gets strange looks.

“People say: ‘Nasty Gal? What’s that?’ ” Ms. Amoruso, now 28, said in an interview at her new headquarters in downtown Los Angeles. “I tell them, ‘It’s the fastest-growing retailer in the country.’ ”

Back in 2006, she toyed with the idea of going to photography school, but couldn’t stomach the debt. Instead, she quit her job and started an eBay page to sell some of the vintage designer items she found rummaging through Goodwill bins. She bought a Chanel jacket at a Salvation Army store for $8 and sold it for $1,000. She found Yves Saint Laurent clothing online on the cheap by Googling misspellings of the designer’s name, reasoning that anyone who didn’t know how to spell Yves Saint Laurent probably didn’t realize his value.