When you are heading toward the snow temple, you will find this specific spot. When you have to be Major ruin to shooot across a gap and switch to Chilla, you should fall. Below will be an elemental fruit and three ice "balls". Get out Ash and burn them; you should get coins in most of them. Wait until they all rebuild, then do it again; more coins will come out. This process is long, but it works. When your wallet is full, buy the larger size and come back to get more coins. Do this until you have 999 coins. Then you can go to shops and by out all their elemental fruit and whatever else you want.