Hey Dan,

Welcome to the club. A full bodied spinner is an extreme challenge and I say that as the guy that drove the Typhoon bots. The forces and challenges involved are ten fold more complex than other designs. A robot with a spinner mounted is still difficult but easier in a number of ways.

Balance board bits won't cut it in the heavyweight division I'm afraid. If you want cheap motors there are a range of scooter motors on ebay around 800w to 1000w in various voltages that are cheap but have been used in robots like aftershock.