You have to be willing to stand your ground when dealing with anybody and anything. They are NOT your BFF. You will not get invited to their BBQ. You will not vacation with them in the Grand Canyon. Their sole and only goal is to get as much money as they possibly can from you. Being a business person myself, if I could sell you air, I would, if you are dumb enough to buy it.
Bargain with the sales people. Remember Saturn's motto, "Sticker price is the price you pay"? They made a point about being having the lowest price and there was no need to argue about it. I got them to argue.
I went to buy a new travel trailer. I researched trailers using the internet dealer's sites to find what was reasonable price. I then picked options I really wanted. I picked floor plans. I went shopping.
First, I did not, and never ever, tell the sales people what you want to spend. "How much did you want to pay each month?" Lips are sealed. "Can we interest you in our low finance plan?" Lips are sealed. "How can I help you get what you want if you won't tell me how much money I get out of you?"
Second, know what you want to offer to buy price. You can most always take 10% - 15% off anything you buy. Anything.
Third, know what options you want and stay firm about it. Resist the "I have this, or I another lot has this, and we can get it in a day, otherwise we wait six weeks." (Don't let them know when you are going out.)
If they don't have what you want "in stock" but have something with your options plus other options that you will have to pay for, demand the unit, and they can take the extra's out. Or you walk. See if that doesn't spur them to lower the price even further.
Good Luck