I need illustration for a children's book.

Good morning, I wanted to know how much you would charge for illustrations for a children's book I am working on? Color would be better but if black and white is better (open for suggestions) let me know.. Its about dementia, title is not entirely decided yet, but open to constructive criticism.. First time hiring online, so a bit scared but your profile looks great..How much time would you be needing? I will attach file with spaces indicating possible illustrations related to page content.
Thank you.