It's uncommon in the aquarium trade. I wouldn't consider it truly rare, but then again. A couple years ago, they disappeared from the aquarium scene for about 5 years; they're showing up irregularly now.
Got one from my LFS last week. I have only seen it venture out of the LR once, and that was about 2 days ago. Very pretty, but mean looking. The last time it venture out is to feed on prime reef.
We have 2 for $100 each at the store i work at. We've heard from our supplier that they have banned collection on them now. Would be a nice fish for commercial breeding! They're sooo cool!