If you are buying something by weight, bring a scale with you. To prevent people from stalling or from providing poor service, find something to threaten them

If you are buying something by weight, bring a scale with you. To prevent people from stalling or from providing poor service, find something to threaten them with. Examples that I find myself saying frequently: "Let me talk to your boss", "I will report you to the authorities", "If you don't follow through on your end of the bargain, I'm going to take you to court." A similar tactic: when bargaining, pull out the money that you're willing to pay, say "I'm willing to give you this much for that item, if you don't accept it, I'm leaving" - and then leave if they don't immediately accept. Usually you will have what you want at the given price within the minute.