I bought a bunch of shells when I was in Florida at one of those tourist shops, I bet you buy those baskets of shells on ebay for cheap, I had to throw half of them away but at $5 a basket who cares. :)
I actually have 3 or four baskets of those LOL...my girlfriend suggested that but I ruled that out cause I thought they might be toxic. Are they not treated to kill bacteria and hitchhikers? Do you suppose boiling them would be all that is necessary?