Consider what it takes to put a gallon of milk on the store shelf. Even at $3.00 a gallon it is cheap and considering how good it is that is even dirt cheap to me.
My wife pays $4.46 a HALF-gallon for the Horizon Organic milk because she thinks it tastes better and lasts longer even though it seldom stays in the ice box more than a few days. Some battles you just concede.
Many stores have loss leaders. Convenience stores as an example are generally more expensive on every item than any grocery chain store and yet often they will sell milk for less than the large chain stores.
Whatever the reason I like paying $.98 per gallon for milk and it tastes no different than the $4.00 per gallon milk.
BTW, the Walmart Super Store a couple of miles down the road sells milk for about $2.50 per gallon.