Likewise, I am not from the Sarnia area, but can offer these suggestions ..... you could create yourself a nice little personalized Shop Hop!
Len's Mills in London also has a good selection of 150th fabrics.
The Marsh Store in Coldstream, just outside of London will have them too.
A few years ago when I was there they had some unique and wonderful Canadian batiks, so they might have them again/still.
Sew Creative in Mount Brydges would be another that will have what you are looking for.
There are several different manufacturers that have put out Canadian fabrics for the 150th, and most stores are carrying more than one of the lines, if not all. Good Luck ... and hope you come on across the border and find the fabrics you want!