As far as Canada today is concerned, Will Bilozir in Alberta does handle quite an amazing array of goodies, all the way from brand-new quality Turkish shotguns to brand-new Charlevilles to reloading supplies to...... Magtech brass.
With TWOSTEAM vacationing with friends on The Island and her Sniders locked in MY sock closet, the pressure will be off for a couple of years and there will be 24-gauge brass for everybody!
Will doesn't advertise here (perhaps he should!) but he is a good guy to deal with. You can get in touch with him at bilozir.net.
He does stock the entire range of Neat Stuff from ballisticproducts.com (the actual importers to North America). They are based in Minnesota (which butts against but is not the same as Manitoba) and so might be a better source for a citizen living in the USA.
And all of that still leaves me with having to set up my small lathe to make some casings for my nice 11-gauge double.
Hope this is some help, anyway!