Bukkit

What is the enhancement in mind? How should it look and feel?

I have a city protection and making new separate regions (child) in it so that players could only do something not to all city, but only in which they are allowed. I'm selling houses in city and I would like to make them automatic. Yes I can make them automatic and now, by putting in sale them but there is one problem. Let's pretend I made 5 buyable  (child) regions and here comes rich player and buy all of them. What I want is that an option so that rich people could only buy one (or more) child region from main region.
Yes I'm aware of permissions that can restrict the amount of how many regions can own a player, but I don't want to restrict them globally.

Second thing I would like to see is that the "/regios list-for-sale" command would have permission, as once again rich people can just look at the list and buy all them by themselves. I rather just put signs near region so that only they could buy by pressing the sign.

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Please provide any additional information below.