We have a cottage in Perth so we are there a lot and I will confirm that the fabric in Canada is terribly expensive. Even I, who has never passed up a fabric store in my life, do not go to stores in Canada since I know that the fabric will cost more than I am willing to pay.
Perth Fabrics is right on the main street of Perth and its a gorgeous town, well worth the visit. My DH's favorite pizza in the world is right across the street at the Perth Restaurant, although we cannot figure out why he likes it so much.
Westport is a nice picturesque town as well. And Ottawa is a day trip for you. Pea green with envy, since I'm not sure when I will get back to the area and our lake.