First time rolex submariner

[Steve Downunder]

Hi,
I am from Australia and new to the Forum and have joined before buying my first Rolex watch, which will be the entry level Rolex Submariner 11610, I thought this Forum would be a good place to start before actually buying, as I know very little about Rolexes.

I intend to buy a new watch to ensure authenticity, this due to the high number of Submariner replicas out there. I also like the relatively new Submariner 11610 design. I have found a person in Australia selling Rolexes on Ebay and although I realise purchasing from a non AD is a risky business, this person is selling a 2015 Rolex Submariner 11610LN, he offers a full refund and says:
GUARANTEED AUTHENTIC, ALL PAPERWORK ACCOMPANIES THE WATCH, but if you're still skeptical, then take it to any reputable jeweler in your area. If any questions arise, upon you returning the watch, I will issue a 100% refund PLUS cost of the services rendered by the jeweler or meet with me at local reputable dealer for an authentication.
The watch has all the original paperwork, warranty card and inner / outer boxes.

I have done research and I am fairly confident I can recognise if a Submariner is original, even compared to the so called "A" grade Swiss replicas, but I am still nervous about shelling out Aud$10,000 for a watch that may not be genuine. Therefore I thought I would ask those with far more experience than I have, if it is worth while buying on Ebay or should I play safe, pay more and buy from an AD. I realise that there will be no 'bargains" if the Submariner is genuine, as Rolex watches have a global price.

The only way I can see anyone able to offer a new Rolex cheaper than a AD here in Australia is if the watch was originally purchased in a Country that does not have sales tax on watches, which is high here in Australia. Am I on the right track? is there anything else I should know before purchasing a new Submariner?

Regards
Steve