There defiantly should be a an in-game Gold sink hole for the upper levels.

There should be a 10,000,000 gold capes
Convert gold to gems 1,000,000 = 10 gems (or something)
Buy craftable items for gold or make the old boss summons work with gold
Make buildings level 4 and 5 for gold.

We need a gold sink hole (a great suggestion that is said and repeated many times by the community, its about time to look into it or at least give us feedback)