To get the best deal, it’s wise to ask a flea market seller for a “best price” rather than making an offer. The reason being: a dealer may go lower than you expected when quoting a price.
For example, if an item is marked $38 your bargaining instinct might lead you to offer $35. But what if the dealer was willing to go to $30? You could get another $5 off by allowing them to state the price.
Don’t be afraid to make a reasonable counteroffer if the dealer doesn’t go as low as you’d like. Don’t be too surprised, however, if they stick to the price they originally quoted. If you can walk away at that price, think about coming back a little later in the day to see if they've changed their mind about taking a bit less.
Take a look at more bargaining strategies in different buying venues: