[kasaasta]

That's a DSSD (Deep Sea Sea Dweller) ref number. For that piece 4k is very, very low - even without papers. I don't mind buying Rolex without b&p but I suggest you have the watch verified by an AD. IF you can get it in a trade with 4k value and it's authentic, it's a killer deal. But seriously, it sounds too good to be true...

 

[kasaasta]

Well, he obviously went diving, wrestled with a great white and the watch just picked up some dirt during that Battle scars, stories, patina and so on!
But seriously, passing that piece sounds like the best thing to do.