for an authorized dealer of Tudor or Rolex, the AD must offer the watch never over list price (at least officially). So, if the AD advertizes it over list price online, its dealership might be revoked by Tudor/Rolex.
But as always, it's caveat emptor (buyers beware) when shopping for second hand products. Please do exercise due care and diligence. Be vigilant. I do window browsing whenever I am near, but I have not bought anything from any of the shops. Happy browsing. Enjoy your stay.
Champagne Building on Kimberley Road, Tsim Sha Tsui (Subway Station: Tsim Sha Tsui, Exit B1). The building (next to the Miramar Hotel) is due for redevelopment, but a number of watch & watch accessory shops remain. There are also used photo equipment shops.