I used Costco for my wedding and was really happy with them, though plan for the assembly to take a very long time! You could also see if any of the florists we have listed on WeddingWire sell flowers in bulk - wedding florists in the GTA
Check out your local farmers market or greenhouses to see if you can talk with a local grower to see what they have in stock. Also some grocery stores are doing wedding arrangements now (our Zehrs in Barrie started a couple of weeks ago). I have also heard that Costco bulk flowers are quite nice. It also depends on the price you want to spend. Good Luck.