Try to look extremely poor, and talk to them about financing. They get all giddy when you talk financing, which is where they make the real money. Then say, just out of curiosity, if I were to buy it in cash, what would the cost be? Then work them down from there, and they'll go lower a lot of the time, assuming you have a woman with you tugging at your arm, "We can't afford that!" Then talk financing some more, and then offer them what you want in cash up front. This way is fun, but take a while.
I like to walk in, find the biggest bullshitter, hand him a card, tell him the price I'll pay, and then walk right out. They'll chase you, trying to make the price higher. Go down in increments of ~$500 while you're walking, and they'll agree after "losing" $1000 in sale, seeing that you mean business. They'll usually agree because they want the sale.
Try to talk them lower, if you get lower, good job, if not, hope you're getting what you wanted for the price you wanted.
Good luck!
-GermyBoy