I've often considered it but doing the math, there is no way to replicate the precise nutrition chickens need that is provided by fresh feed from a feed mill for anywhere near the price.
Producing fresh nutritionally balanced feed is based on the economies of scale.
To make our own feed, we are buying grains and legumes by the 50# bag. Feed companies are buying by the trainload. We would buy the vitamins and minerals by the pound or even the ounce. They are buying by the ton.
Then there is the assay. You likely don't have a lab to determine the percentages of the 38 unique nutrients chickens are known to need.