The Sports Collectors Digest price guides have always been my favorite. I like that the guide includes relative valuations for three card grades and provides a detailed 'how to use' set of instructions in the front. This guide is from 1996 and serves as an excellent reference for average card prices at that time, as well as detailed information about each card set from 1948-1995. There are more recent price guides by the same company for current baseball card collectors.