This 23-year-old gave up a corporate job to make $5,000 a month reselling thrift store clothes through an app

Back in 2012, when she was a student at the University of Arkansas, Alexandra Marquez downloaded the Poshmark app on a whim.

She'd seen it mentioned on social media and was immediately intrigued by the concept.

While it looks similar to Instagram, Poshmark allows you to sell clothing just like you would on eBay.

"I was super addicted from the start," the 23-year-old says. "It was a great way to make money."

Although many of Poshmark's 700,000 sellers use the app as a way to clean out their closets, Marquez had always been interested in running her own business.

She began searching thrift stores for gently used items from department store brands and buying them to resell on the app.

"I'm not going to lie, it was pretty challenging at first," she says. On average, she made $500 a month when she started out - not an insignificant amount, but not enough to live on, either.

Initially, she didn't know which brands and styles would sell on the app, and which wouldn't, so she spent time studying what was popular. Then, she'd go out and buy those items.

To get her listings noticed, she also focused on perfecting her photography skills.

After a year and half, she became a suggested user on the app, meaning that all new users were invited to follow her. That exposure led to more sales, and she began making around $5,000 a month.

By then, she'd graduated from the University of Arkansas and taken a full-time job at a marketing company earning a $50,000 salary. But after a year, she left to focus on her clothing sales full time. "It was a great job, but I decided the corporate world wasn't for me," she explains.

Now, she devotes three or four days of her week to shopping, with the goal of posting several new items every day. Local boutiques in Bentonville, Arkansas, where she lives, often sell their overstock to her at a discount. In addition to making regular visits to thrift stores, she also buys gently used clothing and accessories directly from women in her area.

Most of the clothing and accessories she sells are priced from $40 to $250, and she determines her prices by seeing what similar items have sold for on the app.

Besides buying clothing that she'll later resell at a profit, Marquez doesn't have many costs that go into her business.

She doesn't have the overhead of a bricks and mortar store, and doesn't even need to have her own website.

Poshmark covers the shipping costs and credit card fees for each transaction, so she just pays a commission on each sale: $2.95 for anything under $15, and 20% on anything over $15. After that, she's left with a take-home pay of around $5,000 per month.

Though being self-employed gives her the flexibility to work from anywhere and choose her hours, she admits that she's constantly on the app, no matter where she goes or what time of day it is. "I look at my phone from the time that I wake up until the time that I go to bed … and sometimes also when I get up in the middle of the night." Typically, she lists around 75 new items each month, and ships out anywhere from 15 to 40 sold items each week.

After her bills are paid, Marquez puts most of her extra money back into her business by buying more inventory to sell on the app.

She doesn't live extravagantly, since her income isn't as predictable as it was in her corporate job, and she can't count on making the same amount of money each month. "The only downside is the unpredictability of sales," she says. Like any retail business, hers has seasonal fluctuations, and a slow month could mean she takes home $3,000 instead of $5,000.

But for now, she's happy to trade some stability for the chance to be her own boss.