My guess is that the C2-BK have *recently* gotten much harder to find, possibly due to higher collecting demand.
I forget to mention this. At the time, I always thought that since the C2 is an expensive light, why would you opt for the far less durable finish? I think a lot of people probably thought the same way I did as the C2-BK MSRP was only a few dollars less than the C2-HA. I think it was like $119 vs. $124. It is basically a 6P-BK head and tailcap screwed onto a C2-BK body. Maybe Surefire just made less of them as well for this reason. And the C2-BK might not meet milspec contract standards. Not that I haven't seen plenty of SF type II lights in military cages, like 6P's especially. But, you know what I'm getting at.