hmmm, if you're worried about making offers or trying not to get cheated or cheat yourself in offers and/or trades...what you can do is go to ebay.com...search for the card in question, click on completed listings, and the figure the average of all completed listings...this works well for high-end cards, as it will give you a fair value for the cards in question
btw, I have a Claydol (GE) available for trade if you're interested...I am interested in these:
Magnazone (DP) (holo)
Energy Link (RH)
VS Seeker (RH)
Carnivine G (DP42)
lmk if we can work something out