Need some quick coin? Coin isnt that important of a resource in this game, but for when you need it, you usually need a lot in a short burst. This will help you shortened that grind time!
Step 1: Get the Cursed Skull. This will triple all gold value.
Step 2: Go to Carnival 1 (Level 1-1), and play up to this part, collecting all the coins in the level. then save and quit.
Alternative Step: You can go to Swamp 4 (Level 3-4), and pick up the coins at the start of the level, and then save and quit.
With this, 999 coins is doable withing a few minutes!