The kit you want is the Monsters in Motion one. The ones you most often see on ebay are NOT worth the money and neither is the one sold by Frontier Models. The MIM kit can be made into a very accurate helmet with some work but don't let the 'one-piece' kit fool you. If you want to do it right, it takes a LOT of dremeling - a lot more work than what most folks realize. I'm finishing one now... I think it's my sixth MIM kit and I've finished at least three other versions along with owning three other versions myself over the past five years. So far, the only two kit replicas worth having are the one previously made by a board member and the MIM kit and the MIM kit is far easier to find since the board member doesn't make his anymore.
Rob