IMHO dealing reloading components (and ammunition for that matter) is a business you're either full in or out.
Shipping costs are high, margins are slim, and the big boys ordering pallets of components make it damn difficult to make it worthwhile.
Current Dealer cost for most Hogden powders is $21.95 per pound. Some distributors will allow mixing for case quantities/discount (<5% discount) then there's the $25. HAZMAT tag and UPS/FedEx charges on top of that, then there's supply; Beikirch's in Rochester orders powder literally by the truck load (they have their own tractor/trailer) and for the last three years have only had fractions of their orders filled, same is to be said of primers.
Routinely I see pounds of powder with the asking price of $50. per pound which is ludicrous, and I even think the $35. or so a pound GM charges is outrageous, but for those who need or want it now and have no other suitable source, well they're just going to have to swallow it.
The Shop I associate with stocks a LOT of powder; always has and almost always had powder because when she'd sell it, she'd order it back in quantity to making damn sure it was in stock or there was enough to last if it wasn't available.
Bullets: If you stocked every number Hornady makes except the one that's back ordered, that would be the one everyone wanted
Think of all the different bullets made by the big guys; SIerra, Nosler, Hornady, Speer, etc. how much inventory and money would you have to invest to have a decent selection?
For the most part ammo is in the same boat; I can't speak for other shops, but for the most part there's only a 25% (+/- 2%) mark up: (She always rounds up or down to .95) And they always make sure they have ammunition for any gun they stock. (nothing like buying a new gun and can't get ammo for it; Re:Remington
See to many businesses from Mom & Pop Shops, to major manufacturers, to Dealers, to Government have gotten away from having stock/supplies/parts "on hand" to this "on demand" model; problem is when the supplier doesn't have it because they don't have inventory, YOU don't get it either. We could go into the lean-six-sigma argument, but having been on the receiving end where I can't effect repairs because no parts are on hand, the warehouse doesn't stock them, and the maker isn't doing another run for six months really sucks.