Money-Back-Plus Guarantee. The equilibrium price in the thin market is $2,600. Suppose car sellers provide a special money-back-plus guarantee: A dissatisfied buyer can return a car for a refund plus $100. a. If a lemon owner sells his or her car for $5,000, the owner's gain from providing the guarantee is $ b. If a plum owner sells his or her car for $5,000, the owner's gain from providing the guarantee is