For the 6694, there are many in the market. Make sure you buy from repute dealer and the seller.
Range between rm3k+ to 4k+ very much depending on the condition.
Always make sure it’s a 100% rolex (all - case, dial, hands, glass, crown and of course the movement.)
If the 6694 look too new, be careful. I have seen after market case, dial, hands complete with serial and model number, etc, engineered to precisely to look like an authentic 6694. It very x2 scary.
I have also seen a very nicely build up 6694 with all these after market parts. Only the movement is genuine. Not cheap though...
Now I never trust those buggers selling cheap 6694.
My 2cts
dc