The most I know is 20% off for cash in the UK. personally it is best to get from an authorised dealer.
I don't know too much about rolex and discounts........
I HEARD from a friend that authorized dealers are required to sign a contract where they are not allowed to discount rolex watches else risk loosing their authorized dealer status. I don't know how true that is. It was hearsay from a casual conversation.
I didn't pay close attention as I wasn't looking to pick up one.
Maybe someone else on this forum knows more.....