I ordered one of these from "Camtraptions" in the UK:
Price was 200 GBP ($280 USD, including 40 GBP shipping to the US).
That strikes me as very expensive for a hobby project (I'm going to put a camera that cost less than that in it), but it's the only one I have been able to find for less than $1000+ sold by "security" firms.
I know I could make my own (most online instructions seem to be based on Pelican cases) but I want to save time and buy one pre-made.
I'm surprised - it's easy to find aluminum "security camera" housings (at for example Amazon or B&H) for less than $40. But they're not wide enough for a DSLR.
Sounds like a market opportunity for somebody.