pull down to refresh

I haven't taken the time to think through what the right mechanism would be, but you're right that a uniform cost is probably sub-optimal.
I would hazard a guess that some sort of auction would be best: perhaps having an earning goal in mind and selling enough territories to meet it.
The problem there is that I think they want people to be able to create territories instantly and don't want to be organizing and running auctions all the time.