Some of that is insanely overpriced. Honestly, over $200 for the Darkover Concordance (figuring in shipping, if mailing it to Canada)? You can get it for a lot
less, if you're patient. Still, I'm lucky to have gotten mine back in the '80s, for $18, at a convention. Hardcover, too.
BTW, this seller is sometimes open to offers, if you make it worth their while.
What boggles my mind is the collection somebody insists on selling intact, and he's only asking over $28,000! That listing has been up for a very long time. You'd think by now the seller would have realized that nobody's going to buy it.