Barbara Corcoran shares the $3,000 purchase she most regrets

This is "Shark Tank" investor Barbara Corcoran's $3,000 regret

Self-made millionaire Barbara Corcoran doesn't have to think long about the recent purchase she regrets most: "A Gucci dress," she tells journalist Farnoosh Torabi for CNBC Make It. "Oh God. I hate it. … I'm still feeling guilty about it."

The "Shark Tank" star, who made her fortune in real estate, had a feeling she'd regret buying the distinctive dress. "It's red with a stripe," she says. "It's got a striped collar, that Gucci ribbon thing going on, and I knew it the minute I bought it, it was a mistake. Because you wear it once and everyone remembers it."

The fact that she won't be able to get much use out of the dress frustrates her: "What a waste of money," she says.

It was a significant expense: $3,000 to be exact. But Corcoran, who thinks of money generally as there "to be spent," doesn't just regret the purchase because of the price tag. She regrets it because she barely got any use out of it. The dress wasn't a good long-term investment.

Barbara Corcoran in her $3,000 Gucci dress
Jim Spellman | Getty Images

As it happens, the best investment Corcoran says she ever made was also an expensive item of clothing: a $360 coat that she bought after securing a renter for her first apartment. While it cost a fraction of the Gucci dress, it was a huge expense for Corcoran at the time. She was broke and had just accepted a $1,000 loan to start her own real estate company.

Renting out her first apartment meant collecting her first commission. She cashed the $360 check, "ran right over to Bergdorf Goodman and blew it on a new coat," she tells Guy Raz on the NPR podcast "How I Built This. "I bought the fanciest damn coat: brown and white herringbone with real pearl buttons. Three-quarter length with fur. Real fur, not fake fur. And I wore that coat for the next three years."

The coat also allowed her to dress the part of a successful businesswoman and to project confidence in the cutthroat real estate industry, she tells Raz: "It was the smartest thing I could have done with the money because, in it, I felt powerful."

Like this story? Like CNBC Make It on Facebook!

Don't miss: Self-made millionaire Barbara Corcoran hates wasting money—but she has 2 guilty pleasures

Video by Luqman Adeniyi

Barbara Corcoran, who hates wasting money, has 2 guilty pleasures