If you want to know how to find out the price of your cards for any sports card you need to go to http://www.beckett.com/ Beckett magazine is the card that everyone in the trading community uses as their guideline.
Some will use other guides like Tuff Stuff but do not be fooled as Beckett is the gold standard.
You can get a price on any card that you have at Beckett.
The internet guide is much easier to understand as you can just put in the name of your card rather than having to search the magazine for the price.
The website and the magazine will also keep you up to date on the latest news in the hobby.