 It's free for those living in the U.S. and Canada, $1 per book for those in other countries to help with postage expense. Let me share a letter that came from a kid using Keys for Kids. Grace sent me a very colorful letter with my name on the letter in two-inch high colorful letters with sparklies all over the letter. She wrote, Dear Uncle Charlie, how are you? I love Keys for Kids. In the morning every day, my teacher plays the Keys for Kids radio program for us.