Two identical items can have different value to different people: usefulness, budget, replacement effort and attachment may differ. A seller’s minimum and a buyer’s maximum do not have to match.

Research on the endowment effect examines how possessing an item can affect valuation or willingness to exchange it. Some experiments find owners demand more to give up an item than non-owners offer to obtain it. The size and explanation of that gap depend on the task and procedures; it is not a universal doubling rule.