Pay What You Want is one of the pricing options creators can choose for their products on the Miskatonic Repository.
As the name suggests, as a purchaser, you get to choose what you want to pay for the item (creators can suggest a recommended price, but you can also pay more than or that or even pay nothing if you wish).
Michael LaBossiere, one of the co-authors of the 1995 Call of Cthulhu supplement Strange Aeons, has recently added three "Pay What You Want" items to the Miskatonic Repository that are worth checking out:
Return to the Monolith - Michael LaBossiere (pay what you want - suggested price $0.99, 10 page PDF)
"a modern follow up to 'People of the Monolith' which appeared as a bonus scenario in Shadows of Yog-Sothoth."
The Drooler in the Dark - Michael LaBossiere (pay what you want - suggested price $0.50, 5 page PDF)
"...a Hound of Tindalos? No, far worse."
The Knife - Michael LaBossiere (pay what you want - suggested price $0.50, 6 page PDF)
"...pits the intrepid investigators against a serial killer. Is the killer a mundane murderer or something more?"
What is the Miskatonic Repository?
Are you a Keeper looking for new scenarios and story elements? A player looking for something mysterious to spark a character idea? Is your group looking for eerie ideas to use in your game? The Miskatonic Repository is where you can find —and create —self-published material for the Call of Cthulhu roleplaying game.