Very old wine, Lafitte Rothschild 1918!

[richwlms]

While moving my parents to live near us, we found in their cellar a bottle of Chateau Laffitte Rothschild vintage 1918(among other interesting items). My Dad wanted to drink it but we figured we should at least try to get an estimate of its value. Its been in the family cellar for over 40 years. Can anyone tell me where to find its value?