Gwen, if you follow the link in Tanja’s Post at the top of this page, it will take you to the blog where you will find more info and yet another link, to the pamphlet. I don’t know if it’s been made downloadable or not.
As for what an Illustrator would charge to work with either an Author or a Publisher, that varies widely and is up to the Illustrator and what they feel best compensates them on a project by project basis.