The question that comes to me now is, how to Bud and Coors make their beers for so cheap then?
Quantity. There is a slight difference when you make over 20,000,000 bbls of beer vs 2000. Coors does not use "cheap" malt. Coors Light, Coors Banquet, etc. all use Coors own 2-row barley grown exclusively for them. They do all malting in house in Golden. In the lower end beers like Keystone they use corn starch as the adjunct.
As a single brand, Blue Moon Belgian White outsells ALL of New Belgian's beers combined. During it's height of popularity, ZIMA sold well over 2,000,000 bbls in a year. That is close to what ALL of Boston Beer's brands sell combined.
I guess you simply don't realize the size of the "BIG" guys and what that buying power can do. Miller/Coors SAB and AB/InBev do spend far more on advertising and packaging than on ingredients for each beer.
On a nano/micro level you simply cannot match the volume purchasing that even a small regional can do. There is a difference between buying malt by the bag, malt by the container load, malt by the silo and malt by the train load.
I gave you examples at 1,000 lb levels. You do get breaks at 20,000 lbs and
then at 50,000 lbs. Beyond that I am not sure of exactly the pricing structure. I have never bought beyond 20,000 lbs. That was 6 months supply for a 7 bbl brewhouse. That is less than one days production for the Coors plan in Golden.