I price things a little higher than I want, they offer a lower price, I meet them in the middle which is generally what I really want for the item anyway. For example, Price a pair of sunglasses for $ 5.00 they offer $ 3.00, I say meet in the middle for $ 4.00 most of the time they will go for it because they think they just got a good deal even though I really only wanted $ 4.00 for them anyhow.
Expect people to barter at flea markets. One thing I learned is it depends on what you are selling. If you are selling stuff out of your house and you paid $ 100 for it, don't ask for $ 100 at a flea market, you will not get it. If you sell new items, mark it up x3, and expect to take in x2.
If a person touches something at your table, they are interested. Don't let them walk away. If they walk away, offer it for a lower price to where you are still making a profit, or have them make an offer. Be prepared to counter the offer.
And occasionally you do get those really cheap people who want an item that cost You 67 cents for 50 cents. They won't budge, those type of people you just smile and say "Have a nice day" and move on to the next customer.