Yup, get them at the Community Hall. DD had one and a noodle and crusied around the big pool having a blast! We stayed on DVC rental points and didn't have to pay so I am not sure what the cost is if you are a regular guest.
At the Beach Club this summer they were free -- they had them for pretty big kids as well (up to at least 80 lbs). You just signed them out with your room number. I bet Boardwalk is the same.