Someone convince my wife...please!

[SemperFi]

I joined TRF five months ago and have since been a daily visitor, gathering information, and relying on the expert advice of its members. I've started a few threads and responded to many others during that time and I've come to the conclusion that when I'm ready to buy my first Rolex that it should be from one of the trusted sellers on this forum. My wife disagrees. She believes that going to an AD is the only way to guarantee authenticity and the only option when it comes to a purchase of this size even if it means paying more, and in some cases, much more, plus sales tax.
How do I convince her otherwise? When I respond that the TRF sellers having a long track record of lower priced sales to rely upon she wants to know how they can afford to discount the price of a watch when many AD's will not offer one. Honestly, I don't have an answer. How do they do it? And what argument(s) can I use to convince her that, when the time comes to buy, using a TRF seller would be a safe, secure, and authentic transaction?