Oats are a great ingredient for granola bars because they're cheap, healthy, and tasty. But many people are on diets where oats are not allowed, so we've come up with some substitutes to use in their place. These substitutes should keep your granola bar cheap, but some of them will be healthier than oats and others will be unhealthier. If you choose to use one of these instead of oats, make sure to check the labels on your ingredients to ensure you're still within the dietary requirements for whatever diet you're following.