There are many different types of auctions. The terms of an agreement are determined by the alternatives to the agreement. It requires a credible commitment not to entertain counter offers, i.e. the commitment to walk away from a deal. The exception is Saturn, which sells only at the posted price. This type of posted price allows Saturn and its customers to save on transaction costs.
Grocery stores commit to posted prices.
8 ways to establish credibility Establish and use a reputation. It does not pay to forfeit the bond. Use the courts' ability to punish you if you misbehave to bind yourself to certain courses of action. Cut off communication. For example if you refuse to answer mail, no one can threaten you or offer you inducements to do certain things.