The guy is smart... he has not put other contact info onto the listing... He seems to be located in Littleton, CO which is suburb of Denver. The Littleton Police Department, Jefferson County Sheriff Department, and FBI should all be notified about this person selling this fake Rolex Sub for $750.
We sniff out fake watches as fast as or faster than anyone on the world wide web.
Anybody here can feel free to copy any link on this forum and post it to places like Rolex Forums, Watchuseek Rolex Tudor Board, Adam's new board, Rolexwatchout.com, etc. to help get the word out. Just right click on it here in the forum or Control-C, then click on copy. When you are on the other forum (such as rolexforums.com/watchout) you can hit right click, paste or Control-V to help spread the word about the suspicious watch.