Oh, I didn't realize you were from the Netherlands..you may want to try Goodreads.com, you can find what you want and likely the shipping charges aren't too bad for you..yeah the Cushing and Lee films are cool, perfect for a rainy fall Saturday..
I'm a bit through with ordering through internet, because often you get books damaged. It's really hard, even from major sellers like Amazon, to get a book without dents and damages, because they simply don't package it well.
I may look around some English sections of bookstores, but basically his books aren't around much anymore. They don't seem to get reprints often. When I'm in English sections I just don't see them ever. Well, only Psycho of course, as it's become so famous because of the movie.
But in the US his books are still widely available?
I think I read some of his stories in an anthology though. I don't remember which ones though and if I liked them.
Do you feel the Amicus films (Asylum and The House that Dripped Blood) do the stories justice?