That really doesn't address the 'freshness' or age of the ingredients as a whole...
5kg is hardly considered bulk in my area for most things and won't get me a price break at a grain mill, that doesn't really happen until you purchase 1000lbs (454 kg) or more ...
Cost is also relative, my birds consume about 250-300 lbs (114-136 kg) of feed a week and that is with heavily supplementation of spent grains and fresh produce and sorts, mixing my own based on local price of the raw ingredients would drive my cost beyond reason,and I don't really have the facilities to properly store 1000s of lbs of freed to exploit price breaks...