The folks at Brass Stacker sent me this:
It's pre-production, but I really like it. Good for carrying an extra clip or two! It also adds a certain 'feel' to the rifle. I don't know that I can really explain it.
They are wanting to know what demand might be, so please contact them at Contact Us | Brass Stacker if you're interested.
I have no idea what production price might be.
P.S. I have no financial interest in Brass Stacker. I just like to get the word out when I think a product is useful or cool. J.S.