This is the Rubies Supreme Vader helmet from a few year ago for only $55! It's a great, full size Vader helmet, I used it to make a display for my Dad's home theater entrance a few years ago.
http://www.toysrus.com/product/index.jsp?productId=2265984 (http://www.toysrus.com/product/index.jsp?productId=2265984)
(http://i38.tinypic.com/esje2q.jpg)
Nice! It reminds of the SciFi Museum in Seattle. By wearable do they mean it could fit an average sized adult?