Sure, just like a house appraiser is an independent entity who determines the value of the house... Except that they always take the contract price in mind and basically attempt to not rock the boat. If they can make a case for a valuation close to the contract price, that's what they'll use. If they go too high or low, they risk killing the deal -- and their continuing business with the involved parties. Same problem as with legal arbiters and binding arbitration contracts.