i love the fact that you're using spray cans!
i did my helmet with the spruce green, and while it may not be the same stuff as the movie one was painted with, it's pretty bleepin' close!
as for finding it... that can be a challenge.
i got the spruce green from tk-1776. he special ordered it from home depot i think. iirc, you can special order any color from the brands that they sell, but there is a minimum purchase. i think he had to order a whole case of it.
i like the challenge of getting things to look good with readily available stuff (he says while glancing at the lastest selection of spray cans he bought at lunchtime today)