Home hardwares sell earth worm castings and all different composts fish cow shit etc plus there seems to be one in every tom dick and harry town around lol
As GrowRock stated you can get castings and compost from Home Hardware, Canadian Tire, etc... Obviously check out your local nurseries and garden centers. Another idea is to check on kijiji, locally sourced so even better.
While we are on the subject, I have had a really hard time finding some neem/karanja meal. I'm near Ottawa and found nothing locally. The only thing I found in Canada is from Reindeer's natural, haven't checked the price yet.
I just found out that bat guano is being discontinued for sale in Canada...buy what's left as it is the last you will get according to my grow store source.