For all but the few "lucky ones" that live close to one of the "very few" suppliers, most of us are relegated to mail order.
The suppliers listed above are all well established and trustworthy. I would add Cain's Outdoors (in W.Va) to the list since they were overlooked.
I have dealt with a number of the suppliers listed and I'm ordering from Canada. Have never had an issue, parts were always exactly as ordered, and even with customs delays my shipping times have been "quick".