Wow. I didn't realize how much RJSafety's shipping was, to be honest. Not sure if this is dark enough, but I figure I can get one of each to try:
http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemId=1611771976
http://www.grainger.com/Grainger/wwg/itemDetailsRender.shtml?ItemId=1613548086
For cutting: I've heard that acetate visors can be cut with a sharp pair of scissors, but is that true for ~1/16" material? I'd rather not crack something costing more than the entire helmet in the process :facepalm
Wildabeast, I read about using baking soda and plain white glue for the same sort of purpose, so I'm thinking about giving that a try, (mostly, just because I have a whole bunch of white glue here) but it sounds like the same type of thing.
Thanks for all your help thus far, everyone!