Rex USA 1 / 8

You can't put a price on beautiful hair ... or can you?

For Kendall Jenner, that price is about $4.

The in-demand supermodel was speaking to Allure magazine when she opened up her beauty bag, as many celebrities do during interviews with beauty magazines. In doing so, she revealed the secret to her glossy locks is Finesse shampoo, a $4 product that can be found at most grocery stores.

Apparently her famous sister Kim Kardashian West also uses the product and turned Kendall onto it.

"Kim likes Finesse shampoo, and now so do I. I've tried all the expensive things, too. It just works for my hair and makes it so silky," she said. "My hair has held up so much that every hairstylist has been like, 'Why is your hair still so amazing?' And I'm like, 'I literally don't do anything. I just use Finesse.' And everyone's like, 'What?'"

For Kendall, though, emulating her older sister hasn't always turned out well. When she was just 7 years old she walked in on Kim shaving her legs. Kim, at the time, told Kendall she was too young to shave.

"I once walked in on Kim shaving her legs in the shower. I was only seven and I was like, 'When can I do that? I want to shave my legs. And she was like, 'Not for a long time, Kendall,'" the 20-year-old recalled to Look magazine. "A couple of days later I went and did it with her razor and without any soap or water. I cut my legs to shreds."

She's older and wiser now, obviously. She's also the least low maintenance of her famous sisters, she claims.

"No for real, for real, me. I'm definitely the most low maintenance," she told Yahoo! recently. "My sisters like to take hours to get ready and I'm really quick. I think I get that from my dad."

Low maintenance and low cost.