I found an intresting glitch. if you buy 3 anti grav balls, and don't move them, they make infinite money. you can buy more of these balls in twos, but don't move them or buy another kind. if you buy over 9 balls then it will just break aswell. sooooo, if you want to cheese the game, do this, or if u are the dev, then maybe fix this?
Edit: you also have to buy the grav balls right after one another i think, or maybe it just doesn't always work
ReEdit: nvm, just buy the third bounce upgrade and hope