Concierge.com's insider take:
The days of true flea-market finds may be long gone, yet aficionados will not be disappointed by the depth and range of Paris's markets, and certainly will be pleased by their still-raucous atmosphere. (For further info, check out www.lechineur.fr, which has a complete listing for all flea markets, temporary or regular, in French.)
The Marché aux Puces de Saint-Ouen claims to be the largest flea market in the world—and if it isn't true, it certainly feels that way. There are technically 15 markets in the mass of buildings and stalls, though many now sell jeans and sneakers. Six markets deal strictly in "antiques" and follow a kind of lazy logic: Vernaison is the first off the main drag, with smaller stands and a kind of grab bag of items, from walking sticks to silver to lamps. Rosiers and Biron are the most officious: The stands are sturdier and glassed-in, and the objects might include gold-leafed, double-facing love seats known as tête-à-têtes. Marchés Serpette and Dauphine hold everything from pool tables to costume jewelry. It's probably Marché Paul Bert that has the most pleasingly diverse range, often decoratively worn items, including rare industrial lamps and muslin-covered Napoléon III love seats (Metro: Porte de Clignancourt, Porte de-St-Ouen; Saturdays, Sundays, and Mondays, 9:30 am6 pm). The Marché aux Puces de Vanves is a true brocanteurs market deep in a residential neighborhood in the 15th, a long meandering line of temporary stalls featuring everything from Porcelaine de Paris and tea towels commemorating D-Day to entire vintage kitchens. There are a few excellent art-book dealers and a satisfying variety of silver dealers (for beautiful bone-and-silver salad servers), as well as stalls featuring a broad selection of lithographs, sketches, and even daguerrotypes (Metro: Porte de Vanves; www.pucesdevanves.typepad.com; Saturdays and Sundays 7 am1 pm). At the Marché aux Puces de Montreuil look past the shampoo, polyester nightgowns, and used tires, because this is also one of the better places to look for vintage non-designer clothing, with everything from the late 19th century through the '80s (dealers are mostly grouped in the right-hand corner as you enter from the périphérique), or just to absorb the atmosphere of polyglot suburban Paris, where herb hawkers mix with rug dealers and battery vendors. For occasional finds in china or mid-century French café ware, elbow your way to the back by the bridge (Metro: Porte de Montreuil; Friday, Saturday and Sunday, 7 am7:30 pm).