I'm lucky enough to have a fertilizer producer in the next town.
They make literally dozens of formulations at your request.
Cheapest all mineral stuff is $5.75 for 50 lbs. High sulfur coated products can be $8.75. 50 lbs of Pre-m or Team is $10 a bag.
They sell Shaw's as a commercial line with pesticides.
I was told that the difference in cost has to do primarily with the bag! Those string tied bags are more expensive than what I get.
Luckily, mine have nice looking exteriors. Seems customers get upset when they see brown paper.