Both HPL's and REH's work are now in the public domain. Check Project Gutenberg or your favorite PG-scraping site for their (mostly) complete works.
In the case of REH, this has led to an explosion of REH pbooks from various publishers, with assorted commentary, illustrations, etc. I think I'm collecting three different series of them now, along with my old Frazetta-cover paperbacks. Plus, of course, the ebooks. Can you say "addict"?
