Here are two examples
The first is a Grant with a 5/8" extension and priced at $6800.
http://www.hillrodandgun.com/picture.php?id=12876This gun is too expensive for my wallet, but even if I could afford it, there is no way I could live with it at is. I might, in the case, slice off the extension and live with a leather pad. Maybe.
Here is a second gun that was priced at $5500 and apparently sold. It is a Churchill with a 2" extension. This would be a restocking project so far as I'm concerned and it's too expensive at that price for me to consider in that light.
http://www.hillrodandgun.com/picture.php?id=12855So, of course, these are only my feelings and VERY uninformed opinions, but I am curious if I am in the same ballpark as most people or not.