I understand that fee is for charity. it's also probably designed to cut down on the volume of his fan mail.
That's pretty much it. I got the same thing a few years ago.. I replied to the email on the sheet and pointed out how much $$ other people charge like HOFers for example. The reply was along the lines that it didn't matter what everyone else charges and that this is for a Childrens hospital. They did tell me to re-send my item though at no charge... which I did.