Not sure if they still have Tung Fong Hung Medicine shop in Chinatown, but I would highly recommend it, especially if you are new to herbal medicine. Tung Fong Hung is a trusted brand(so you know you will get exactly what you asked for).
Tung Fong Hung Medicine Co. Ltd. (Main St， Vancouver
G/F - 536 Main St， Vancouver， BC,
There are also other locations:
147-4800 Kingsway， Burnaby,
8031 Alexandra Rd， Richmond BC
954 Lansdowne Centre， Richmond,