you could maybe try to send the light back to get the lens replaced under the warranty.
i think all you would need is two channel lock wrenches with some sort of rubber or other protective material (so as to not scratch the light) to break the thread lock. or maybe just a vice clamp and a channel lock wrench. i've opened thread locked heads before pretty easily. of course yes, you would void the warranty if you opened the head.
if you can get to the lens, just measure it with a caliper or something similar and go to flashlightlens.com and see if they carry that size.
i was considering doing that when i first got the light, just to have some extra lenses, but decided against it. i'll just wait until i break the lens before i try to replace it. however i did get an extra grey grip, two extra switches and five extra switch boots.
do me a favor: if you do happen to get a measurement of the lens (diameter and thickness), let me know the dimensions so i can order a couple extra for mine.
good luck!