It's being introduced in C5 - it will involve some fishing and a few mini-games to conquer it, and I really hope this one will fall to smaller clans who can be bothered with such carebearish things.
With the clan/ally related changes in C5, and the new clanhalls coming - I think the price of the halls will go down a lot from what it is today.
It certainly should, if the whole Clan/Alliance consolidation thing is real. Then again, some people don't mind having a 1 man clan holding a CH or Castle.