Simon's Weighted Blanket

Simon is 12 years old and autistic.  He *loves* hanging out and piling on the blankets.  We've learned about weighted blankets, ones that provide the pressure that he loves so much.  We're hoping to be able to purchase one, but weighted blankets for a kid his size aren't cheap.  We've been trying to win one every chance we get, but so far no luck.  So we thought it might be good if we tried to do this another way - creating our own "contest," so to speak. 
Please help if you can - even if we can't buy the extra large one we'd like, we're hoping to at least be able to buy him a medium-sized weighted blanket.