We call ourselves Marketplace, so part of our job is exploring how marketplaces work, in all their forms. David Brancaccio and the “Marketplace Morning Report” team set out to visit five markets, all in the near-orbit of this program’s world headquarters in Los Angeles. None are financial markets in a formal sense, but all markets are financial markets in a way, right? The goal is to learn the right and the wrong moves with an expert.

Today, the tricks of the trade in one of the great American bazaars: The Rose Bowl Flea market in Pasadena.

Entering the Rose Bowl Flea Market around 6 a.m. on a September day, there’s no sign just yet that the temperature is going to climb to 117º F in just a few hours’ time. This stadium, where college football plays its big New Year’s Day game, has more than 89,000 seats. So imagine its massive parking lot filled with sellers of “vintage”… everything. A beer tray from the 1984 LA Olympics, for instance. A century-old Russian dress.

Annette Vartanian is Marketplace’s guide to this place. She wheels along a market cart for all of her great finds. “It’s like an appendage when you come to the market,” she says.

Vartanian is editor at A Vintage Splendor, a guide to all things vintage, thrifting and more that boasts tens of thousands of Instagram followers and YouTube subscribers. Along with that market cart, she’s got a white, straw boater hat for the sun, and she’s brought actual cash.

“Let’s say you negotiate something, and it’s $110, you only have $100. You’re giving them $100. The vendor’s happy, you’re happy,” she says.

Or, cash can come in handy to leave a deposit on something and come back later. Another trick is to come with a plan, but be open to things that catch your eye.

“I always kind of just scan. I call it T. rex eyes. You gotta look up, you gotta look down. And you just move to the target as fast as possible,” she says.

Leafing through a stack of wall art, Vartanian looks for signed works that are ready to hang to save money on framing. She likes a nice portrait, including a boudoir-ish one. But she has limits.

“There’s, like, two things I will never buy vintage. No. 1 is anything with, like, a clown or an antique doll motif. I mean, that’s just, like, guaranteed to give you nightmares,” she says, laughing.

Vartanian also sees price tags as mere conversation starters. For her, one negotiating trick is to mix it up.

“I will ask, like, what’s the best you could do on this? Or could you come down to $400 on this, but I’m also throwing in the delivery because I’m not carrying this out myself. Can you throw in, you know, a bundle deal if I buy multiple pieces from you?”

Less than halfway through this shopping expedition, and the temperature hits triple digits. Is that a mirage or is that lemonade for sale rolling through? But there are upsides to this kind of heat, according to Vartanian.

“Extreme weather days are the best days to come to the flea market,” she says. “If it’s pouring rain, they want to sell stuff. They don’t want to take it back. And if it’s a really hot day, they don’t want to spend two hours packing things up to take them home.”

This market is like four-dimensional chess: One set of sellers focus on the super-curated, hand-picked selection, where you might pay extra. We stumble across dresses that belonged to a famous dancer from Russia, early to mid-20th century pieces.

Another dimension of this market: digging through piles. There are sellers set up in ballroom-size tents, displaying hills of camouflage wear or soccer jerseys — sellers like Tony Torres, founder of Torgom Vintage.

“We have dresses, sportswear, sweaters. We have everything here,” Torres says.

Beyond the flea market, Torgom Vintage is an industrial-scale used-clothing enterprise working out of massive warehouses in California and Texas. Torres buys wholesale by the truckload and railcar. The business has over 5 million pounds of clothing ready for customers, he says.

The final categories of sellers to navigate at this flea market: variety versus specialization. On the one hand, there’s a vendor selling a 1950s ashtray, a Bolex movie camera and a Bob’s Big Boy statue all in one spot. On the other hand, you have operations like the Phonograph Co., run by brothers Jeff and Steve Oliphant. They know their hand-cranked gramophones inside and out and offer a lifetime guarantee. Jeff Oliphant cautions that you need expertise to spot slick fakes.

“It’s called a crapo-phone because they are pieces of … and they are guaranteed to fall apart within a short time after you buy it,” he explains. “You don’t see it with the Edisons — they’re too complex. It’s with the Victors. Victors have a metal tag; the fake ones have decals.”

Meanwhile, Vartanian — indefatigable in the blast furnace heat — has her T. rex eyes scanning for rugs, furniture, even Victorian underwear that works as a modern blouse.

“You just have to go for it because, I mean, you’re not going to regret buying it,” she says.

How does she keep the buying from getting out of control, though?

“It’s kind of like the vintage circle of life,” she says. “I find something, I use it, and I maintain its quality. And then when I’m ready to part with it, it goes to the next person.”

Find all of our Tricks of the Trade stories here.