I have not seen Halloween things in the stores yet, but I am sure they are there. The other day when I went in to The Quilt Block in Exton (610-363-0404) there was this adorable trivet on the counter. One of the owners, Jan said they used to make them with knitting all over them instead of fabric.
So besides some bottles caps and cute Halloween or any other fabric you choose, this is all you need.
Stop in and ask Jan or Cynthia how to make one, they will be happy to show you.