how much should used tires run?what a fair market price should be.so what i should be looking for
Think to yourself, Why are the tires being replaced? Because they were not good/safe enough to be run on the last persons vehicle. I never recomend used tires as you're buying someone elses problems. The only time I would ever recomending a used tire is when you have 3 good tires and 1 thats damaged and needing replacement, trying to track down one of the same type with the same amount of tread is the only time I would ever recomend used tires. Tires now adays are cheap for some brands, take a look at Kelly, GT Radial, Continental, Hankook and some of the other low end sister companies to brand name tires (like Kely is sister to Dunlop Tires). Some offshore brands are half decent as well, I would personally go after a cheaper tire then to buy a used tire. I've seen some starting at $40/tire, and up, depending on the size and style. Plus, unlike used tires, you will get a manufacture warranty (depends at times, sometimes they ask for proof of purchase), as well as warranty from the company that installed them.
