Costco buys huge batches of inventory from suppliers and when its gone it maybe a while before they get new stuff in,if they in fact do. They are not that loyal to any one supplier although if its their own brand name like Kirkland they most likely will restock.
There's another costco in Mississauga on Dundas near the 403 which isn't that far from the Novatel if you've got a car and is bigger than the one on Mavis. PM me if you want directions.