Penny Bowers-Schebal has worked in retail, sold insurance and owned a wine shop. Today, she lives and works on a dairy goat farm.

She also owns and runs Formality Bridal, a wedding dress shop in a 4,000-foot abandoned church in rural Geneva, Ohio. Bowers-Schebal, 55, buys last season's sample gowns from larger retailers and resells them locally at a discount, for up to $999 each.

It's a lucrative side business: Formality Bridal has brought in more than $400,000 in revenue so far this year, according to documents reviewed by CNBC Make It. Bowers-Schebal devotes 25 hours per week to it, and pockets about 20% of her store's earnings, she says.

Formality Bridal wouldn't be profitable without the decade Bowers-Schebal spent as a sales manager for insurance giant Progressive, she says — where she made "slightly" more money, but lacked a sense of fulfillment.

Specifically, that job taught her how to build "strategic relationships," she says. It's the No. 1 lesson that helped her build Formality Bridal without any previous experience in the wedding industry, she adds — because convincing other bridal shops to sell their past-season gowns is more difficult than it sounds.

Using 'strategic relationships' to become profitable

Used wedding dresses represent a small but growing industry in the U.S., as more brides rebel against rising costs and paying thousands for an item of clothing they'll only wear once.

But even among consignment shops, Formality Bridal is considered particularly affordable: Its priciest gowns are roughly $1,000 less than the average wedding dress in the U.S., according to The Knot. Its local market is small, too: Geneva is a town of less than 6,000 people.

These facts present a profitability challenge for Bowers-Schebal, which she tackles in two ways.

First: When she cold-calls dress shops with her sales pitch, she purposefully avoids other stores in her region, focusing instead on ones in other parts of the country "that would not have considered me as a competitor," she says.

Her sales pitch is a little more complex than "I'll buy the dresses you can't sell." She keeps the names of most of her partners confidential, for example, and removes any tags that could identify their stores — because "bridal designers frown on unauthorized retailers having their gowns," she says.

Taking a hands-on approach

Second: Once she strikes up a relationship with another store, she takes a hands-on approach to inventory selection and price negotiation.

When Bowers-Schebal visits one of her partners, Something White Bridal — a small luxury boutique for new dresses just outside Cleveland — she parses the racks, identifies up to 50 gowns she wants to buy and negotiates the prices herself. Sometimes she eyes up dresses with minor stains or seam tears, which she brings to a local seamstress or dry cleaner to mend.

Most consignment shops don't do that: They only purchase a few dresses at a time, all of which must be in perfect condition, says Something White owner Rebecca Somnitz.

Something White is geographically closer to Geneva than most of Formality Bridal's partners. Somnitz is the reason why: She learned about Bowers-Schebal on Instagram, and sent her a direct message.

Somnitz could easily sell some sample dresses to other consignment shops, too — but currently, she only works with Formality Bridal. That's largely due to Bowers-Schebal's personal attention to detail and insistence that each transaction benefits both parties, she says.

"She's realistic about what her customers will pay and how she can still keep a profit," says Somnitz, adding: "She has a good eye, too. She'll say, 'You can tell that this was a $6,000 dress because of the fabric, lace, construction and seams.'"

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