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.
We don't stop playing because we grow old;
We grow old because we stop playing.
---George Bernard Shaw