Book illustrator

Information for the business: illustrate a book on nutrition
Industry: Sports and Fitness
Design details: I have a book with editor on nutrition and weight loss. In each chapter I have explanations which would be a lot better if accompanied by an illustration. My idea is to send someone my sketch of what is needed and then a pro would pretty it up to a publishable quality,
Im guessing 12-20 total illustrations, some will be chart like
Illustrations to show processes (circle and arrows type thing) or for example to show different body shapes (simple line drawings) or to show an example of a protein or of the GI tract
looking to send this work out march/april
Ideas for the visual style: modern
Things to avoid: too detailed
Where the design will be used: self published book
Extra notes: book is with editor as the moment. Im hoping to do illustrations in next month or so so that they can be ready to be added to the work once it returns from editor
would probably pay per illustration unless otherwise agreed
open to suggestions on how to price this job