When I lived in Grimsby I bought my worms in bulk from Grimsby Tackle, no problem.
If Grimsby can't help you Bill's Bait and Tackle on Upper James in Hamilton sells worms in bulk too.
His prices may actually be better as well.
And you're right to bring them, believe me.
I've done (I think) 33 fly ins over the years as well as countless weeks paddling and fishing northwestern Ontario.
Yes, there's many instances where bait is redundant.
Then again there's been plenty of times where they'll double your catch. No need to take a chance on that for the sake of 30 bucks worth of worms.