Update: For those of you unfamiliar with baseball cards these days, but are still interested in following prices, here's a quick reference guide for some of the terminology used in the following charts. (If you have other questions you'd liked anwered about card terminology, feel free to ask).
Refractor - all refractors (X-fractor, blue refractor, gold, etc.) are just normal cards, but printed in limited runs (usally 500 cards or less) and in different colors. Some colors are more rare than others.
Au - autographed card
BC - Bowman Chrome card brand
BS - Bowman Sterling card brand
/199 - card was numbered to only 199 copies
Donruss EEE - the most recent Donruss printed card brand







