Hi I saw your bike and am interested in buying it
Great! Thank you for your interest. I am willing to part with it for 650 and not a penny less.
Well it is 13 years old...is that the least you'll accept for it?
Tell you what... For you, I will go a bit lower. How about 600?
How about 550 and I'll pick it up tonight?
550 sounds like a great deal. I accept it and you can pick it up tonight.