What you need:

• Stretchy body parts (available from Cost Plus, World Market)
• Treat boxes (available from Cost Plus, World Market)
• make-up remover pads
• ketchup or fake blood
• small white bandages (if you want to wrap the body part instead)

N.B.  You don't have to use the exact supplies I have listed.  You will be able to find treat boxes at party stores or decorate plain ones with scrapbooking paper.  Body parts can be picked up from your Halloween superstore or most places that stock halloween decorations and supplies.