The most important skill to have as a flea market shopper, besides perhaps having a good eye for high-quality items and good deals, is the ability to barter well. The concept of a flea market is built entirely on the practice of haggling -- unaware customers can be duped into giving away more money, while intelligent shoppers get a good deal on a product that didn't cost the seller too much to begin with. A savvy barterer can make sure everyone wins in the end.
Approach the seller you've chosen to buy from and express interest in the item in question. Ask questions about it -- get the lowdown on specs, quality, history, anything that you need to know before you confirm a sale. Even if you are certain you're going to buy it, still inquire as if you aren't sure. This plays into the next tip...
Don't seem desperate. If you do, they'll know you're more likely than not willing to pay a much higher price than the item's actual value, and will refuse to barter with you. Don't act disinterested, but don't be overeager, either. Strike a balance between the two that will put you on equal footing in regards to power with the seller. If they start to push you, back off and accompany your statements with lots of shrugs and noncommittal gestures.
Name an unreasonably low price to start out with. At a flea market, rarely will a seller laugh you off, because they figure they can at least try to bargain (and therefore keep your business). The worst they will likely do is laugh and then name a very high price. Your job is not to panic, but to work up in small increments as they work down in small increments until you reach a reasonable price.
Go into the bartering with a bargaining chip -- perhaps the name of another vendor who has a similar item, or the idea that you'll take your business somewhere in the retail field. The threat of losing a transaction is a better motivator for a seller to give you a lower price than anything else; if they refuse to go anywhere near to a price you named in your head ahead of time as one you'd be willing to pay, you can always whip out that bargaining chip.
Consider bartering if the stall owner is a small-time business. Maybe you know how to cut hair, design a room, or train a dog. Offer one of these skills in exchange for a lower price on the item.
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