Keep in mind that there have to be at least two items on the negotiating table. There must be something you want more than the other, and vice versa for the other party. If a lower price is what you need, what can you offer---rapid purchase, or purchase-for-sure, or what? Some dealers might give the lower price if you just ask for it, and others might need to see that you are serious about buying. And, some won't dicker.
Are you ready to buy, now, if the dealer cuts the price, what?, $200 or $300 or what? Know what you want and what you'll walk away from. If you need a lower price, be sure the dealer knows for sure that you'll walk.
"What made women act so outlandishly,
with so much predictable unpredictability?
Soft and fluffy on the outside,
jagged and prickly underneath."
Jussi Adler-Olsen, "The Marco Effect"