Hello
Hello are you interested in buying this BMW?
Yes, I am interested in buying the BMW.  Unfortunately, I'm really only looking to spend $4200 on a vehicle.  Would you be willing to lower the price if I come to you and pick the car up?
For this car I think that is a bit low. 5000 is a great deal for a car like this! I'll even throw in a gas card that I have for you to use. 
That is a nice addition and I'm willing to raise my offer to $4350, but I'm afraid I can't go any higher than that.
If you can come by and pick it up today I'll sell it to you for 4350.