I called a bunch of area anodizers a while back to anodize one light and some bicycle parts, and most of them were willing to do a batch that small, although sometimes you had to wait for it to be put with a larger batch. I ended up having the bike parts ano'd through a bike shop in Milwaukee, and sold the bare Al light.
I can't remember all of the companies I called, but here two of them which I think I spoke to, both of whom do Type III Mil-Spec anodizing:
I'd recommend going in to see their facilities and samples of what they've done, and even bring in the light you want ano'd and see if they'd do it. A phone call or email can only go so far. Both of the above companies seem pretty top-notch... and they're somewhat close to eachother.