I would suggest Instagram for sure. There are plenty of people who are showing off their watches. Take a look at this account for example: http://instagram.com/thebillionairesclub

You'll see a lot of photos with premium watches being tagged from the original store accounts. You can leverage by sparking conversation on those pictures, follow hashtags, make one of your own.

If your product is good and you execute this well you can definitely get some momentum.

The key is to think beyond your first 100 or 1000 sales. How do you service those customers, do you get them to spread your product? What incentives do you give them?

These are few questions worth pondering on.