Write Short and Concise Books.
Instead of writing a 500-page book selling for $50 (which probably few will buy), write a 100-page book and sell it for lesser which greatly increases the number of buyers! ...It fits in Amazon’s price range of $2.99 — $9.99 (gets 70% royalties for ebooks). Anything lesser or more gets 35% royalty. This is for the ebook version. Paperbacks have a different price structure. You can price them higher with higher royalty rates.