Your dealer is not telling the truth. You can trim at least 4K more. Be persistent and adamant. Talk cash purchase, not financing through dealer's sources. If you can get an auto loan from your bank or credit union, get the approval for the max you're willing to pay for the vehicle, and slap the letter of credit on the dealer's desk. Talk to the desk manager, and know who the owners are. Sometimes owners WILL take a low offer (especially in this climate), because they have different agenda/priorities than the grunts that work for them.
Unless the owner himself turns you down, don't walk away.
Cash talks, and you have the upper hand (they have a car they need to get rid off, and they want your money!).
Don't fall "in love" with the vehicle. Walk away if the deal can not be made,....by the end of the month they WILL be calling you.
Good luck.