When I say that Brit Eaton was in the doghouse, I don't mean that he was in trouble with his wife. I mean he was literally inside a dog's house, with just his boots sticking out the door.

I shone my flashlight over Brit's back to watch as he picked through the layers of old rags and clothes making up the bed of the occupant, a heeler with a baseball-size cyst on her belly. The dog's owner, a sixtyish rancher named Mike, from Modena, Utah, was too distracted to pay much attention to his visitor's behavior. Just that morning, Mike had learned that a mountain lion had somehow infiltrated the eight-foot-tall fence surrounding the headquarters of the Meathook Ranch, which his grandfather had established in 1903. He was cautiously watching a juniper thicket above a corral of calves. "I'm a son of a bitch on following tracks," he was saying, "so you better believe when I say it was a big cat." Mike turned back toward the doghouse and was surprised to see Brit's backside. He pointed a thumb at Brit. "People make money all sorts of ways, don't they?"

Brit, 38, is of medium height and solid build. He has a stern, square face that would be suitable on an evening newscaster if it weren't for a tangled scar above his lip that resembles a strand of barbed wire. He makes his living scouring the old ranches, ghost towns, abandoned homesteads, and forgotten antique shops of the American West in search of vintage clothes. When most people hear the word vintage, they think of bell-bottoms from the seventies, but Brit's definition of that word goes many decades deeper into American fashion. He has a particular interest in denim workwear from the late 19th and early 20th centuries. His company's name is Carpe Denim, and he sells his products, or "pieces," to a disparate array of clients, including Hollywood wardrobe departments, private collectors, and companies like Levi's, Ralph Lauren, the Gap, and Dickies.

He is unabashed about his prowess; he freely admits to being "the best person in the country at finding old clothes, maybe the best in the world." In a career spanning more than ten years, he has found hundreds of thousands of sellable vintage-clothing items. He once sold a pair of chinos with links to a soldier from the Spanish-American War to a Japanese collector for $12,000, his personal record for a single piece, and he's discovered as much as $50,000 worth of clothes in a single day. Brit is deathly afraid of competition—there are a handful of other vintage-denim hunters—so he's skittish talking about money. It's clear, though, that he earns an annual income pushing well into six figures.

Despite these numbers, Brit has yet to find a piece that approaches the pinnacle of the vintage market. In the summer of 2008, an eBay seller going by "Burgman" auctioned a pair of circa-1890s, candle-wax-encrusted Levi's that he claimed were found in a mine in California's Mojave Desert. On July 30, the bidding closed at $36,099. In 2001, an anonymous person sold a pair of 100-plus-year-old jeans, discovered in a Nevada mining town, on eBay through Butterfields, a San Francisco–based auction house. The jeans were purchased by their original manufacturer, Levi Strauss & Co., for $46,532. With stakes this high, Brit isn't eager to reveal his hunting grounds, but I'd arranged to spend a week with him on what he calls a "denim safari" and had met up with him at his warehouse, in Durango, Colorado. He was in good spirits; the day before, a couple of designers from Dickies had visited and made a substantial purchase. The warehouse is a garage-like structure with overhead doors, chaotically stacked wall to wall and floor to ceiling with plastic crates of vintage clothes bearing cryptic labels that Brit himself can hardly understand. "I hide stuff from myself so I can't sell it right away," he said. "It's a retirement plan."

From the warehouse, we'd driven to Brit's home, on the outskirts of town along the Animas River. In the morning, he said goodbye to his wife of four years, Kelly, and their three-year-old son, Zealand. Brit loaded a barebones collection of camping gear into the back of his Toyota Tundra and we headed west toward the Great Basin, between the Rocky Mountains and the Sierra Nevada. "There's a chance we won't find anything out there," he warned, "but it's the best place to be if you want to find something that's going to shake up the world."

Late the following morning, we'd rolled into Modena, Utah, a once-thriving railroad community reduced by time to little more than a ghost town. The bank, hotel, and bars were all closed and permanently shuttered. The only sign of life was a middle-aged woman in a sedan who was sorting mail she'd pulled from a P.O. box. Brit's intuition suggested, correctly, that this woman lived on an old ranch, and he stepped out of his truck to make the somewhat preposterous suggestion that she let him dig through her closets and attics. Earlier, Brit had complained that the rain was a detriment to this particular approach. "People associate storms with strangers and trouble," he said.

If the storm didn't scare her off, I was thinking, Brit's clothing might. He was wearing an olive-green 1940s canvas hunting vest, oversize 1950s fatigue pants, beat-to-hell leather boots of indeterminate age, and a white henley-style shirt from the 1920s. He explained to the woman that he pays good money for the sorts of things he was wearing and that it's not uncommon for him to fork over a thousand dollars for a piece that most people wouldn't even give to the Salvation Army.

"You know how kids nowadays buy jeans that are faded and full of holes?" he asked her. "Well, clients rely on guys like me to find things for design inspiration." The woman looked at Brit as if he were asking her to strip right then and there, and she said that we better talk to her husband, Mike, about eight miles up the canyon. "But wait an hour," she said. "He's dealing with a lion right now."