purchasing new or pre-own rolex ( any discounts from any AD?)

[honolulu168]

Greetings!
I would like to purchase men's and women's datejust with diamond dial/two tone rolex watches for my parents. However, the rolex authorized dealers in honolulu won't give any discounts. Do any of you can recommend any authorized dealers in mainland that offers good discounts? also, if I don't purchase the watches from the authorzied dealers, what are the disadvantages?
How about pre owned? I saw couple preown rolex from Tourneau? is it good to purchase from them? I don't think they are authorized dealer though.

Thank you very much!