It’s 10,000 money, 3+ bondage and 3+ drone level. It would show you this information if you hover your mouse over the button, but if you are playing on a phone, such functionality may not be available. Really need to do something about this.
maybe add like a double click system where the first click shows requirements and shows the info that the items does and the second click being to confirm the purchase. And possibly have this as a toggle options in the game setting in the Home Screen.
