Thanks for reaching out to OkadaBooks. We don't have a fixed price for books on OkadaBooks; we leave all of that to you, the author. You can put any amount to sell your book(s).
Fun fact: The less expensive your book is, the more downloads it will get.

The image below contains trends from actual purchases over the last 3 years.

We believe they'll help give you an insight into the best pricing structure for your book.