* bump *
It's been my experience that these have been trending downward for some time now. There were some "glory days" I remember from about 2-3 years ago where the whole Metagaming TFT line sold like crazy: $50 per book, over $100 for the set, etc. Every auction had lots of bids and most ended with a sniping frenzy ... ah, the good ol' days.

Disclaimer: I don't track TFT with nearly the regularity that I do certain D&D items. Maybe those books are back to getting solid prices.
YMMV.