Aside from the very pointed out unbalance issues, i think the game would benefit of more variety, more modifiers for the wheels, maybe negative money o division intead of multiplication; or even one that can destroy your wheel's. More than unbalance i believe the real issue is a lack of challenge, making this a complete mindless "number go up" experience. Which is fine, but if that's not what your after, definitely something worth working on.
Very good Submission, great luck :D