Ravi wanted to sell a collector's item cricket ball that his grandfather gave him from the match between England and India in the first Cricket World Cup of 1975.Ravi was unsure about the worth of the ball but thought that perhaps the best way to get a good price would be to auction the ball at an event for cricket enthusiasts.Ravi does some research online and decides to sign up with an auction agent for sport memorabilia (Memo Auctioneers), to auction his cricket ball at a charity event (Ravi felt his grandfather would appreciate the gesture).All the items at the charity auction are listed for the guests and Ravi's 1975 CWC cricket ball is listed 'without reserve'.At the auction, Shelley, a keen cricket collector, bids A$300 for the ball.Nobody else bids for the ball.Ravi is furious, as he feels that this is far beneath the genuine worth of this wonderful collector's item.Shelley argues that as she won the bid, she is now the rightful owner of the ball. The worth of the ball when appraised by an expert is assessed to be A$2500.

Advise Ravi.

Please use relevant case law to support your answer.