Quoted from JethroP:I will always negotiate the price over the phone if I have to drive more than an hour, or unless I am already willing to pay the advertised price. If it is something I want, I want to know know what it's going to cost before I make the trip. Once I get there I don't need to negotiate anymore.
Agree with this.
As a buyer I'm going to negotiate the price beforehand based on the description, pictures, reputation of the seller, etc. If it's not what it is purported to be when I show up then maybe I'll leave empty handed.
As a seller I'd appreciate the same. Don't show up and waste my time nitpicking and trying to talk me down in price. I want to represent the game accurately so there are no surprises when you show up and you know the price before you make the trip.