In the pursuit of greater wine knowledge I have found the greatest expense to be in the wine.  It takes a lot of wine bottles to truly “understand” the nuances of each wine region both great and small.  The second largest expense for me have been the wine books.  There are an endless amount of books covering everything from encyclopedic to specifics; from terroir to marketing.  I have found though that even with an extensive wine library there are a handful of books that are my “go to” selection in starting any wine related research.