In Calgary, I've used
Wood Depot and really like their kiln dried birch. Not even remotely cheap and I am bracing for mockery from the manly men who go cut their own in the bush. But hey, it works for me.
According to my email archive, I have used
these guys in the past, but their website and name has changed so I'm not sure it's the same outfit still. They seem to be Alberta wide now. And BC.