It's a classic trope of entrepreneurialism: A hobby grows into a passion, and a passion grows into a saleable service, skill, or product. A day job is abandoned in favor of making the hobby a full-time venture. Many craftsmen, chefs, artists, and retailers have lived this story.

Sites such as Etsy and eBay cater to this type of start-up, but many entrepreneurs still opt to debut their goods at local flea markets. And the timing couldn't be better: Communities around the U.S. are showing a rekindled love for handmade and vintage goods, locally-produced artisan-made crafts, and vintage clothing and housewares. Between economic uncertainty and the desire for simplicity and sustainability, more people are shopping at flea markets.

The greenmarket trend in the food world is also spreading more widely across the U.S. If you can pickle, preserve, brew, or stew something your friends request every holiday, maybe its time to take your creation to a larger audience. So how do you launch a business at a local market? Here's some advice on how to get started.

Flea Market Start-ups: Testing the Waters

When your hobby – be it block-printing stationary, crafting goat-milk soaps, or designing up-cycled lighting fixtures – shows enough promise to justify renting a stall, selling at a local flea market could be worth a shot.  Most street fairs and markets have a very low barrier to entry: You'll need transit, a table, a tent (for outdoor markets), a cash box and the ability to contribute a small booth rental fee to the market's organizer (usually $25 to $50 for small communities and $75-$125 for urban fairs). If your community doesn't have a flea market, look for seasonal markets or even neighborhood street fairs.

Even if you're already successfully hawking your wares online, making periodic appearances at craft fairs, art shows, and flea markets can give your business new insight into the market, your regional competition, and local consumers' evolving desires. Think of a flea market table as a pop-up retail store, says Amy Abrams, who founded flea market Artists & Fleas in Brooklyn, New York, in 2003. 

"I really think people have used it as a mini storefront," she says. "What we have found is that we were always a low barrier to entry, and though over the years we've grown from about 25 to 50 spaces, we never wanted to be too big, because we want every one of our vendors to do well."

Community markets like Artists & Fleas can serve as barometers for the rest of the retail market. For instance, Abrams says seven years ago she found herself begging North Brooklyn vintage stores to set up booths at her weekend flea market. Now, due to a great sales record at New York-area flea markets, there's sometimes a glut of vintage merchandise – and sellers compete to have the best collection and most knowledge to win customers.

"Our philosophy has always been that the market will always tell us what works," Abrams says. "A flea market is one of the best places in the world to see how people respond to your stuff. We've seen hundreds of people go on to use this as a platform to do what they really want to do. "

That was perfectly true for Nadia Georgiou, owner of childrenswear retailer Brooklyn Junior. She had decided two years ago to sell screen-printed children's clothing when her husband found a flier on the street announcing the opening of the Brooklyn Flea, another market in the New York City borough. She signed up and, two years later, is still an active vendor.

After only several weeks of work, Georgiou says she got a better sense of how to build her business. "I was very fortunate because, being at the flea, I was face-to-face with my customers and what they liked, who they were, and also they told me what they would like to buy," Georgiou says. "They gave me a lot of ideas."

Flea Market Start-ups: Learning to Think Like an Entrepreneur

Designer Amy Adams started her ceramics design company, Perch, more than seven years ago, mostly by bringing her hand-crafted lamps and vessels to trade shows, where she would sell to retailers at a wholesale cost. When flea markets started popping up in, she jumped on the opportunity to sell her own goods to customers at full retail price. Moreover, flea markets became a place for her to try out new products and gauge interest "At a flea market, that's when I bring new things, or samples, to get a feel for how people feel about it, how they are reacting to it," Adams says.

For vendors at the Brooklyn Flea, the atmosphere is also ripe for learning from other vendors – and collaborating with peers. This is especially true of the growing food and beverage sales wing of the market, which has become something of a social network for culinary entrepreneurs.

Susan Povich is the owner of Red Hook Lobster Pound, which for the past two years has been bringing fresh lobster to Brooklyn from Maine. She says the Flea is an ideal business incubator, and not just because she sells hundreds of $15 lobster rolls each weekend day at the market. If a vendor need a hand with anything form a business form to a supply-side issue, they're always surrounded by peers who can help, she says.

"We ask each other everything from 'How much was your insurance quote?' to 'Where do you get your hot-dog buns?'" Povich says. "For instance, when I contracted insurance brokers, I got the quotes and sent them around to the other vendors in case they needed them or were interested. It's such a wonderful community."

Povich got one great idea from one of the Lobster Pound's neighboring vendors, AsiaDog, a business that sells inventive Asian-topping-decked hot dogs. AsiaDog initially grew its business by setting up weeknight pop-up shops in Brooklyn and Manhattan bars. Povich seized on the idea and started branching out to alternative pop-up locations for selling her bisque and fresh lobster.

For vendors who make crafts and handmade goods, the sense of community is equally strong. "You just start up and have no idea what you're doing at the beginning," Georgiou says. "But all the people are very helpful. I would find out how to talk to customers, how to grow my business, where to get supplies." She also found other designers whose products she loved; these connections grew, and she eventually identified suppliers whose goods she featured alongside her children's clothes once she opened her own boutique.

Flea Market Start-ups:  Building a Loyal Customer Base

At a time when many customers are changing their buying habits, building loyalty is critical. That's especially true for sellers of handmade goods who either run – or aspire to open – a retail space.

Fortunately, flea markets, especially weekly ones, can be ideal vehicles for creating loyal customers.  That's because there's an emphasis on one-on-one interaction – and customers know that the designer, artisan, baker, etc., is usually the one doing their own sales.

Abrams, who founded the Artists & Fleas market, says she's seen hundreds of vendors grow their customer base solely through showing up with their creative wares each weekend. Some years ago, a musician named Gabe Molnar showed up at Artists & Fleas with a bag of t-shirts he'd created – he hadn't registered for a vendor space, but Abrams gave him a break.  Molnar became a regular vendor and, within months had such success selling at the market and on Etsy that he needed to spend all day screen-printing to keep up with demand. He couldn't even spare a Saturday to sell more at his booth.

A start-up's efforts shouldn't begin and end at the market, however. Most vendors have websites on which they sell their goods or promote them, Abrams says. And Twitter has become an important tool by which companies can alert their best customers to special deals and where one-day sales can be found.

"All of my employees are trained in the product, and they can all give you essentially Lobster 101 – and that's what's required at the Brooklyn Flea," Povich says. "No one wants to just be tossed a product at the Flea. They want to talk to you; they want to meet the owner. And then they will come back."

Flea Market Start-ups: Stepping Away from the Folding Table

Despite the flea market's ability to help educate new businesses owners and help them develop a loyal customer base, there are some parts of the pop-up shop lifestyle that aren't so great. If flea-market table-surfing isn't your dream job, first figure out what is. If it's opening up a store or running a website, use your time at the market to work toward that goal.

How do you know when it's time to quit your day job and focus full time on your passion? "My big thing is, I don't think you should quit your day job until you have money in the bank," Abrams tells her vendors. "It's really a question of when you have enough momentum and you have revenue from more than one source, and you know that you can cover your living expenses plus a cushion."

Abrams also suggests artists early on develop an awareness of seasonal fluctuations in sales, and learn to husband cash. You might feel great when you have a surplus after a great holiday season, but you need to remember that the cash will go to stock up on supplies for next year.

For Perch, the lighting business run by Amy Adams, the big moment came after seven years of flea market sales. By day, Adams worked at a lighting design firm; at night, she designed merchandise on the side. At the point when more than 40 retail stores were selling her goods, she finally decided it was time to fly solo.

Her advice for designers starting out? "Stepping away from the day job probably takes longer than most people would want. Because then you are paying for a lot more stuff, including health insurance, you'll need to have a lot saved or a really reliable income."