You cannot use Amazon or Ebay as your basis for values of books. In either case, you'll have some sellers 'fishing' with a crazy value to see if someone who didn't do their homework bites. And it pays off enough to keep that going.
I am seeing values dropping sharply in RR books. There's a Milwaukee Road book that until a couple of years ago would sell for way over $100, but I've been routinely seeing them for a fraction of that price in the past year or so. I got mine for $30 not long ago.
Having sales tables at model RR shows in the last few years, I've watched railroad book values drop off sharply in the secondary market, even for newer ones. I got a few good Morning Son published books for about $20 each at a recent show and they retail for around 60. And even in that case, the seller had dozens of them at that price and nobody was stampeding to buy the others.
