At first I though lvl 11 Collectors was hard to get but now when im lvl 67 and still going hard I think that adding a few more upgrades wont hurt and will help us grow. I was thinking up to lvl 14 or so. I thought it would be a good idea because some upgrades are demanding like 3,000,000 is kinda tough for me when I get 100k and plus taken every couple hours. I think the Dark Elixer pumps are fine for now as D.E. is not as demanding.
Both the Gold Collector and the Elixer Collector end with 168,000 for 11.
For the prices I was thinking the following:
lvl 12:220,000 or so
lvl 13:340,000
lvl 14:480,000
rough estimation not final price
I do not have pictures only the ideas.
It would be nice to have higher collectors and mines, but this is what the game is about. Raiding and fighting, if you are going to constantly sit behind a shield and farm what fun is the game? Build your army and go raid others.