The Bank is a place where, if needed, you buy bucks and gold from in the game.
Pinch: $0.99 Pocketful: $1.99
Gold, even though the same price as Bucks, is actually way more expensive, as it is 10x less than Bucks in value.
Upon entering the Bank, Buddy will immediately begin asking you to spend the money.
A mini version of the Bank will pop up on the screen if you try to buy an element that you don't have enough for, along with Buddy making fun of you.