Nice!
There is an old collector here in town that had most of the old Arkham House hardcovers signed by August Derleth. One of the small time dealers in town sells the books for him. The story he gave me is that this gentleman started collecting comics, pulps, and sci-fi/fantasy books in the late 40s and kept his collection going into the 60s. Unfortunately, he sold off his GA and SA comic collection during the late 60s and early 70s as he felt the prices had peaked!
He still has some of the HC books left (although some have been sold to dealers in the US or in auctions), including a few Arkham House books that he and a friend took a road trip to get signed by Derleth. I have been trying to get my hands on them for a few years now but he is not parting with them yet (I have had to settle for his non-Conan Grants, first edition sci-fi paperbacks, and some unread 50s sci-fi pulps/digests/ for now).