Chickens are omnivores with complex nutritional needs so I would be cautious with making or growing your own feed. You can do it but you should do a lot of research and planning to be sure they are getting everything they need before you proceed.
Look at the feed you are buying and make sure you are happy with it's nutritional content. To cut costs you can consider supplementing a feed as long as you still keep nutrition in balance.
I would recommend reading about fermenting feed as a way to increase the nutrition of the feed you are buying and some people find they are then going through their feed slower. And reading about growing fodder as a cheap and easy way to grow food supplements. Mealworms are also a good, cheap, high protein snack that can be farmed at home.