I have 2. A silver one and a 25 year Weyhauser Gold one. I have been getting $40 each fo rthe silver ones and I won't sell the gold one. The problem with the aluminum (here in Washington) you can't buy them any more but you can still use them. If you get caught with any dents then it is $400 per dent fine and so is not worth using as they dent real easy.
Blaster is right about the tin heatin up. Its no problem on the wet, cool coast but the summer sun here will cook your noggin, there is a big diff between the plastic and metal. I have seen them on ebay.
Here is a old one. It is complete with a cut and numerous pictures scribed into it. There is a real nice picture scribed into it of a woman who forgot to put her clothes on.