Do you spend a ton on little cups of yogurt? You can get a starter culture for yogurt or kefir online easily nowadays, if you don’t have a friend-of-friend or neighbor’s-grandma to get some from, and make yogurt at home by feeding it some milk every day.
Or, do you love crusty sourdough bread? Get a sourdough starter going—it can survive being neglected at times until you get around to making bread. And once you do, chances are you won’t want to stop.