Pre-Owned Rolex Purchase Advice

[deedledoo]

Hello Rolex forum. I want to buy my son a pre owned Rolex for graduation. Not the super expensive vintage ones, but a lower end watch. I have seen these on websites like Fashionphile - who "guarantees" authenticity ( I have purchased other luxury goods from them), but I am nervous about where to buy one. Frankly, if I got a good fake that has a seconds hand that moves smoothly, I would never be able to tell it was not real. Can anyone recommend a place to purchase one that is reliable? Thanks!