Can tourists safely buy traditional chinese medicines in Hong Kong?

My acupuncture doctor is willing to write a diagnosis based on pulse reading and toungue appearance. If I present this prescription at any of the chinese medicines stores in Ko Shing Street, Sheung Wan will I get help from a herbalist to decide what medicines/teas to take? Are there english speaking herbalist in these stores who can help? Also I do not want to spend too much money to exceed the permissible limit at Hong Kong customs. Whats a reasonable amount? Can I request them to give only vegetable source medicines? Is it safe to consume these herbs this way?