If you get a free ticket to a performance of the Phantom of the opera at the Shanghai Grand Theatre, suppose you can't sell or transfer it, and you learn that it's the last day of the exhibition of French Impressionism at the Shanghai Art Museum, which you've always wanted to see. If tickets to the Impressionist exhibition are $400, the maximum you are willing to pay is $500. If you end up going to the Phantom of the Opera, what's your opportunity cost?