The items show cost and amount when they're already maxed. You may want to consider using "MAX" instead of 1/1 and displaying "Bought" instead of the price once something has been bought. Though you may want to leave the actual max amount in for elements that have more than 1 upgrade stage.
Other than that, great progression! It's much more fun when you don't have to wait for hours. Although filling the first two stars might be a bit too slow for my taste, since you're only waiting for it to fill without any way to speed that up substantially.
