So I like to use a couple of ghost writers I have found on various freelancing sites (Upwork, elance, etc). Don't let their rates scare you away. Almost all of them work for fixed prices. I let them chose the price, then I add a bonus on top of that.

A story can cost anywhere from $50 for a 20 page novelette to $2500 for a full novel.

As a terrible writer, some times I provide my own short story, then work with a professional to plan out something bigger. I'm currently working on a 200-250 pager with a guy I found on upwork. This will cost me about $500 for the writing, $500 in bonus, $500 for proofing and editing, then I have a novel with full ownership - he will be on the byline if I ever decide to publish it.