The key is to be a critical consumer. Does the stuff look well made? Feel well made? Seams tightly stitched? Bare fabric ends welded or otherwise treated so they can't unravel? Zippers good? Don't be fooled by too many bells and whistles. Sure, maybe a more expensive jacket has reinforcement patches on the elbows, but do you really need them for the $50 (about $3,758 Canadian) more than that reinforced jacket might cost?
And check the fit. That's particularly important for boots and packs. All outdoor clothing is pretty generically sized, although there are differences in how voluminous one piece is versus another and that may matter to you. But if the boots and pack don't fit, then that matters-a lot. So take some time there, testing different brands of boots in several sizes, and trying three or four packs on, each loaded with 20 or 30 pounds.
Bottom line: You can shop happily and MEC, and come away well equipped.