Sally bought a used computer from Polly for $300. Polly told her that the price seemed fair but that she really had no idea what it was worth and just wanted to get rid of it. Sally, who knew little about computers, thought she had a great deal. After Sally returned home, she discovered from a computer expert friend of hers that the computer was not worth as much as she believed. Sally wanted to return the computer claiming that they were both mistaken about value, but Polly said, "No way!" Who should win in the dispute between Sally and Polly and why?