  A seller posts a price for a single object. The seller's and buyer's values
may be interdependent. We characterize the set of payoff vectors across all
information structures. Simple feasibility and individual-rationality
constraints identify the payoff set. The buyer can obtain the entire surplus;
often, other mechanisms cannot enlarge the payoff set. We also study payoffs
when the buyer is more informed than the seller, and when the buyer is fully
informed. All three payoff sets coincide (only) in notable special cases -- in
particular, when there is complete breakdown in a ``lemons market'' with an
uninformed seller and fully-informed buyer.
