Do you live in the U.S.A/Ca/ Other Country? If you live in the U.S.A you'd most likely be able to find one for around $40+ in a local head shop. I paid around $42.00 in at a LHS in CA for my Gas Mask.
Everyone coming in on this thread and hating.. It is not a waste of time. It is another way of enjoying natures greatest plant. Personally I like gas masks because they can send me into a paranoid high which is fun at times haha. Love it in the woods especially, easy to carry and use!