That's up to you and how desperate you are.
What are the estimated taxes and licensing fees for the car in your area? In my state is was over $1500 so you have to take that into account.
Besides it sounds like there is still some negotiating room. This was the first price he quoted you over the phone, and sure he will try and hold to that for a while. If you are willing to play hardball go there in person, talk to the guy, let him do his thing, and then write down the number you want. He'll disappear for a bit to "see his manager" and probably come back with a counter offer. If you feel you are getting played just get up to walk out and then they will usually give you what you want (they'll never let a potential sale walk out the door).