I'm designing a role playing game set in a Lovecraft-inspired world, and I need some kind of currency in it. The obvious one that comes to my mind is just gold, but since in rpgs atmosphere plays a very important role, I'd rather find something more original — or at least have some background story as to why gold is considered valuable by cultists and such.
In other words, if you were a Shub-Niggurath worshipper, what would you pay with for a copy of Necronomicon?
Is there anything in the mythos (Lovecraft stories, or Lovecraft-inspired stories) that is of particular value to cultists? Maybe something abstract like vitae? I'm open to any ideas.