When zombies take over and feast on your brains, the survivors are going to need a new currency. That currency is Zombucks. Coins that depict historic walkers. And I ain’t talking George Herbert “Walker” Bush. That was a whole different kind of monster.
Forget bottle caps and bartering. Use the currency of your current shambling and rotting masters to buy what you need from other survivors. You can choose from many sets and designs.
Will you be broke during the apocalypse? Yeah, I probably will be. Why should things be any different under a zombie regime?