What kind of salary would a life coach make?

My mom is seriously looking at becoming a life coach for people, but she doesn't have a clue what kind of money they make.
She's not very good with computers or the Internet, so she asked me to post this on here, in hopes that somebody had a general idea.
I know it would be difficult to say exactly how much they all make, since it probably varies, but even a rough estimate would be greatly appreciated.
Thank you for your help.