Have no idea re availability unless they are just not big sellers. I doubt I would have bought one if I had not tried it with David Hemmings. I was convinced that I needed to use my Gitzo and Wimberley to get good BIF with the D800. Now that I know I can use the BH successfully with the D800e, I use it almost every day. We live on a lake, and there always birds coming by. I just shoot for practice if the scene is not great.