Why on earth do $500 jeans exist?

That's the question Douglas Keeve -- the director behind the iconic 1995 Isaac Mizrahi documentary, "Unzipped," as well as 2005's fashion-competition flick "Seamless" -- set out to answer in his Web-only series "Dirty Denim," which focuses on the California-born premium denim market.

In the four short films, now on the Sundance Channel's Full Frontal Fashion site, Keeve delves into the supercompetitive premium denim industry through the eyes of the designers behind Chip & Pepper, J Brand, Hudson Jeans, Serfontaine, Degaine, and Henry Duarte.

"When I started hearing stories about the denim industry, I was shocked at how much more hard core it was than the rag trade," Keeve tells StyleList.

"It's bigger, so obviously the stakes are higher. And it has to do with the special nature of denim itself. It wasn't until I did this series that I realized that jeans are expensive and difficult to make. And, as with producing any fashion collection, a lot can go wrong, but even more so with denim."

"It's a very dirty business," Pepper Foster, half of the identical-twin design duo Chip & Pepper, tells StyleList. "Everyone thinks they can get in, and it's so tough. [The film] gives you the inside view on how hard we work."

The documentary goes behind the scenes at the few washhouses outside Los Angeles that develop the washes and hand-worked styles which are then duplicated around the world, often with cheaper materials using computers and machines in place of humans, giving an inside look at the cut-throat and sometimes sleazy denim business.

It also focuses on the beginnings of the $200-plus premium denim market -- attempting to explain the craftsmanship behind those soaring price tags -- and the boom-and-bust cycle brought on by the economy.

"Denim took a major hit, and for us, it's just about regrouping," Chip Foster tells StyleList about Chip & Pepper's method of staying afloat in the recession.

"We have different divisions. We have our premium denim, and we have two brands that are lower-priced jeans, C7P and Foster, which are unbelievable and just on fire, and you can buy them at JCPenney. We've adapted."

Jeff Rudes, co-founder of J Brand, says he's focusing on collaborations with hot brands like Hussein Chalayan and Proenza Schouler to keep his company relevant, as well as sticking to J Brand's relatively affordable price point.

"When we opened, the market was flooded with high prices, but there wasn't added value in $200-plus jeans," he tells StyleList. "But I saw long-term, and there's been a correction and the competition has brought the prices down. We opened up with a price point of $140, and right now the volume is at about $158. Our business has been up, and we haven't felt the recession at all."

Which might also have something to do with the brand's clean and easy-to-wear style.

"We have a timeless product," says Rudes. "We are the black Chanel clutch bag of what we do. Or that black Armani suit that you can rely on. We are that, and that's what fashionistas aspire to."

As for Keeve, who started making fashion documentaries more than a decade before "The September Issue" and "Valentino: The Last Emperor" came around, he says more exciting projects are in the pipeline.

"We have a television show produced by Fox 21 that's set in the fashion world, created with Ryan Murphy, who is the guy behind 'Glee' and 'Nip/Tuck.' So that's in the works," he tells StyleList.

"And about 12 years ago I followed Polly Mellen around; she's one of the great doyennes of fashion. She's pretty much retired now, but the footage is amazing."

"Polly has worked with every single great photographer on earth. She was trained under Diana Vreeland, and she did everything from the Nastassja Kinski-and-the-snake photograph with Avedon to amazing Helmut Newton and David Bailey photographs," he says. "I'm working on finishing that film, which is very exciting."

And, of course, StyleList just had to ask him about the hundreds of hours of film -- we're talking vintage Kate, Naomi and Linda in their heyday! -- that Mizrahi says Keeve has left over from "Unzipped." Could it eventually make its way to a theater?

"I like to look forward and not backwards," Keeve says. "However, whenever you make a documentary, you always have five movies, not one. And it would be really nice to explore some of that other footage. So, yes, I would love to do that."

Drool.

Until then, head over to Full Frontal Fashion to watch Keeve's "Dirty Denim."

Also, find out why fitting into old jeans is better than sex.