Kim's Nature sells bonsai, pre-bonsai, nursery material, pots, soil components, and some tools and wire
Bonsai House sells bonsai & pre-bonsai and has a wide selection of pots
Sheridan Nurseries are a great source of nursery material and have a selection of bonsai and pots
Humber Nurseries have a great selection of nursery material and a small selection of bonsai and pots
Canadale Nurseries has a huge selection of nursery material and will order special material upon request
Nurseries Ltd.
Lee Valley Tools now carries a line of bonsai tools
Connon Nurseries has a huge selection of nursery material
Northland Nursery is a good source for inexpensive nursery material for beginners to pratise on
 
Vineland Nurseries is a good source for unusal and dwarf evergreens
Tropical Expressions supply bonsai to garden centers in Ontario and Quebec
Plant World is another source for nursery material
Hortico Nurseries is a good place to scout for nursery material