The collecting community tends to use Beckett's Price Guide as the standard baseline for valuing cards, but there are several other card-pricing guides available that list the value of each card. The available publications include Beckett Sports Collectibles, Tuff Stuff, Sports Market Report, and Sports Collectors Digest. For the most part, these guides do a pretty good job of setting prices.
A card's value is determined by a simple case of supply and demand, but the card's worth to the individual collector will always vary due to the collector's individual preferences. In short, it just all depends on how bad a collector wants a particular card! The prices in these guides are intended to be a reflection on how difficult a card is to find (the supply) and how popular (the demand) the card is within the card collecting community.
For example, Vintage Yankees and Dodgers cards usually sell for more money than players from other clubs. Many people will collect the players from their favorite team and just because those teams are located in highly populated cities, have many fans and have historically had very good ball clubs.
When I came up with the concept for Dean's Cards, I designed the type of eStore from which I would like to purchase baseball cards. My original goal for Dean's Cards was to create the easiest and quickest way to buy vintage cards - not necessarily the cheapest. As it turned out, the prices of cards at Dean's Cards are very comparable