The problem here is that you think customer negotiate out of free will because they enjoy the process. They negotiate because they are so distrusting of the sales process at most dealerships that they feel if they do not negotiate they are being taken advantage of. The reality today(especially in used cars) is that you do not need to negotiate as a dealer. If you do, you are giving gross away. If a customer walks into your showroom to see a vehicle they have already decided that the price was fair. If it wasn't why would they be there? Because they want to practice their killer negotiation skills? What a shopper needs today is reassurance that the 12 or so hours they have spent researching this big decision was done correctly. Validate for them that the price they saw online was fair. Tell them how you go about evaluating the market the same way they do and that's why the price is so competitive. Being one price can be done from a position of strength. It just takes discipline to stick to it when someone says they are leaving over $100.Good point!
If customers don't want to negotiate......then don't. Just write the check.