agreed, now that collecting has more or less hit mainstream, prices fluctuate too often to be tracked in any books. Any real value can only be derived by checking the several collector's forums and ebay.
If i recall correctly, these books also had brief descriptions of games and maybe a screenshot or two? Or am I thinking of another release. I wouldn't mind having a printed encyclopedia of every modern game, but I kind of doubt this is that.
Maybe OP can show some pictures of what is inside.