We still purchase smokeless powder, primers and certain bullets Stateside, but apparently they aren't allowed to sell us Black powder or any 50 BMG components.
I do believe brass is also a no-no.
There isn't a big difference in cost of bullets & primers but most powders are approx.$17.00 per lb. or roughly half the Canadian price.
I still buy all my loading dies direct from the U.S. manufacturers with no problem...don't know about presses.
We can still buy certain long guns from the local dealer in Lynden and for a small fee he will deliver said firearms to the Canadian Border Post for registry.
Hope this helps...