Used car haggling

The first thing I would advise is, don't shop a payment.
The next is wait until the end of the month. That's when the salesmen are trying to make their #'s and cover their draw. They are more likely to come down then.
Don't discuss a trade in until you have settled on a price for the car that you are buying.
Stick to your guns and don't be afraid to get up and walk away.
I've seen salesmen work a deal, and have a customer get up on them, they will try to work with you. They get paid nothing until the car is sold.
That whole go talk to my sales mgr about this price is B/S. They should have a sheet with the stock# and min sales price of each used unit. anything over that # is theirs plus the hold back commission. They know what they can sell a car for and no conversation is needed.