In no particular order, some of the places I have bought supplies from:
Tenda for primers, sometimes powder. Over a certain price is free shipping, but you have to pay the "dangerous goods" fee. I think. Been a while.
If you are local to GTA, there is Hummasons for powder, and some primers, lead shot, some projectiles. Their hours are not great, but their prices are usually good.
X-Reload, they have a good smattering of everything, watch their prices and shipping.
Lawry is another, usually good prices, but their shipping can be spendy.
Mystic Precision, Jerry can get you projectiles, brass, dies, and has a wealth of knowledge on F-Class and other disciplines.
SFRC has some reloading supplies, I have bought Hornady projectiles from them (at the store), they were a good price.
Budget Shooter Supply, I have purchased shot, hulls, and wads.
Western Metal, they usually have a good stash of brass.
BlackSheep Brass, I'm not sure that he has the 50AE, or 308, but if you're into 9mm, or 223 and need lots of fired brass that is ready to load, get in touch with him.
Kind of depends on where you're at.