Lvl 12 mines and collectors

Hi guys,
I think it would be awesome if ther were level 12 gold mines and elixir collectors, its really frustrating not making very much money at higher levels because some buildings are very expensive, i think you should get it at town hall level 9.
I also want to say that you shoul be able to pay even more gems to triple the gold/elixir collection eg. if a level 11 mine/collector was already doulbled you shoul be able to triple it for a further 22 gems.
Please tell me what you think.