i think these price guides are whack. they only go with what is hot at the moment and then they dump them later. its somewhat ridiculous that a 2001 Chris webber insert could be worth like 50-100 times his rookie card, and as soon as a new set comes out that one drops like crazy.
but that's what they're for. they're for the value of the card at that time. they don't predict what it's going to be.