I recently purchased a FLIR device for "hunter education"
What I have found is this.
1. There is NOTHING else like it for spotting critters.
We regularly go for drives and look out of an automobile moving at about 10mph and are able to spot MICE on trees 30 feet into the woods and raccoon's in tree tops 40 yards in the woods.
2. Deer think they are invisible in the dark.
You can stop and observe deer standing in fields at distances of 30 yards to up to about 150 yards very reliably in the dark
3. There REALLY aren't as many critters around as you might imagine.
4. If the world changed and you HAD to feed yourself somehow, you wouldn't want to be without one of these.
5. The internal battery in this item scared me at first. I figured it wouldn't hold a charge for a realistic amount of time to use it. I was wrong. I only have to charge it after about 3 full length outings.
6. It is indeed expensive. But may be the best money you could spend in an emergency
7. The potential for poachers to use this for bad things is real.
8. Day or night, winter or summer, this is a real diamond.
9. Yes, you COULD mount this on a firearm, but it is far more useful as a hand-held device