I'm considering getting some of the missing ones on DVD. I didn't realize how many were Karloff films. I see Universal put out a February 2018 DVD release of:
Boris Karloff & Bela Lugosi: 4-Movie Horror Collection (Universal)
- The Black Cat
- The Raven
- The Invisible Ray
- Black Friday
With these DVD releases, you can collect a chunk of the other movies:
Universal Horror: Classic Movie Archive (Universal)
- The Black Cat
- Man Made Monster
- Horror Island
- Night Monster
- Captive Wild Woman
The Boris Karloff Collection (Universal)
- Tower of London
- The Black Castle
- The Climax
- The Strange Door
- Night Key
In the above Universal Karloff Collection, Night Key is the only film in the Shock Theater list.
Boris Karloff Collection - 6 Movie Set (Mill Creek)
- The Black Room
- The Man They Could Not Hang
- The Man With Nine Lives
- Before I Hang
- The Devil Commands
- The Boogie Man Will Get You