"Ghostwriting a book generally runs between $15,000 to $40,000 -- depending upon the complexity and word count. A complete line editing job runs about half that. The job is broken down into 3 or 4 payments. Ghostwriting or comprehensive editing ONLY takes about 60 to 90 days.

We charge $1,500 per 10,000 words (10,000 words is about 40 pages of
double-spaced, 12-pt font text). Unusual formatting (complicated
tables, figures, etc) is extra. Simple bulleted or numbered lists,
pagination, headers, references, and so forth are all covered under
the basic ghostwriting charge."

"no one good enough to do a half-decent job on a book will charge less than $5,000 and most will want [and deserve] more... for a real pro, you may have to shell out $15,000 and up..."

"signing a deal to split the advance/royalties/whatever after a sale,
isn't worth the paper it's printed on, because there's no guarantee
there will be one... a sale, that is... which is why only amateurs
will agree to a backend payment and work for months, essentially for
free..."