hey Ghastly!
I would say "Welcome to the Boards!", but looks like you have been here a long time, just never post.
Anyway, that is one of my fave Graham Ingels covers, although I admire basically anything horror he did.
As for that CoC, well, I believe it to be one of the more tough books of the run. Harvey's generally are easy to get, & in fact I myself have had TWO copies (although neither in high grade), but it does seem to come up for sale alot less than other Harvey pch. However, I would not rank it as "scarce" by official Overstreet standards.