Originally Posted by
The Flicker Fade
There is no easy answer, as I'm sure you have discovered.
I can tell you that I've watched listings sell on ebay of books with damage to the extent of the photos you've shared, and they all sell for 50% or under of the going price of undamaged copies. This is in the US of A, though, where copies of these books are more easy to come by. General scarcity in NZ might bump that up some.
The degree of the damage matters. Blunted corners isn't so bad. Spine damage and splits or tears to cover material are really bad for resale-ability prospects. Damage to the binding is unsellable. Your Colossal Conan is probably completely fucked, for example, but I'd be surprised if your Absolute Planetary wouldn't fetch about the full market price since that's just some very minor slipcase damage.
Good luck, and don't let that adjustor cheat you. But remember, it's really just stuff, and most of those books would still read perfectly anyway. That means they still serve their function!