They don't get big enough. I'd pass on that particular specimen. The white stripes on the cheek and head should be bold, like a clownfish's stripes. That poor thing looks faded and beat up. Also, you'll likely never see the thing in a tank of your size. Much better in a 10 gallon nano or something to keep a close eye on it. Even then, they are incredibly secretive. You might catch a glimpse at feeding time for a couple seconds, but that's about it.
If you do get one, and can get a good shot, Scott Michael is looking for a good picture of one.