Like a 'Kelly's Blue Book'
A BUC book is a listing of boats and their values, very similar to the 'blue book' used for cars. The easiest way to get access to one is to ask a boat broker or marine surveyor; Many will let you flip through their copy. There's an online version at http://www.bucvalu.com; BUC also has an online site, found at http://www.buc.net. Good luck!--Jon Bastien