Stars Helmet Cover

i'm making a mask with a long visor. in the past when i make a mask with any kind of tinted or covered eye holes i use cheap sunglasses lenses. but now i'm making something that has a visor. the "Star wars Clone Wars" clone troopers helmet or Boba Fett's helmet have smiler sized and shaped visors. i'm looking for some kind of cheep tinted material i can use for this. maybe some kind of plastic? i have a hard time ordering anything online so anything i could buy at Ace, Walmart or kmart would rock. It doesn't have to be "one way" something that has the same level of tint on both sides will work as long as some light gets through.
Plexyglass is to hard. i need something that has a little give. again it's being fit to a helmet. friend of mine said acetate, but i wanted to know if i had any other options