I have made capes out of twin size black flat bed sheets. They're $5 at Wal-Mart. Just find the middle of 1 edge of the sheet, and cut straight to the opposite corner on the bottom. Do the same on the other side.
According to Vincent Price, when he and Peter Lorre went to view Bela Lugosi's body at Lugosi's funeral, Lorre, upon seeing Lugosi dressed in his famous Dracula cape, quipped, "Do you think we should drive a stake through his heart just in case?"
Painted this years ago using two 12" clay pots for the body, a 10" pot for the head and a clay saucer for the base. Finish with a cape and fill the head with treats. I love bringing this out every Halloween, and the pots stack for neatly for storage.