John - I think that's a pretty cool piece of artwork. He looks sinister. I'm also drawn to to those kind of quirky sketches (usually one of a kind). I have a nice original sketch of the actor John Dall (GUN CRAZY, ROPE, etc.) signed by him.
That looks like a signature by Karloff. I can't tell though by the scan if it's in fountain pen. Could be pencil. HFS will provide more images that are usually more hi-def. of the item if you ask.
And yes, as Eric suggests, make-an-offer if you are serious about it.
I’ve purchased two autographs in the past from them and made an offer both times that was accepted. I was considering offering $450 on this, they have it at $510.