[Question] Online watch selling protections?

Hello all - I'm not sure if this belongs in the simple question thread or another sub. If so I apologize and please let me know the right place for this question.

To keep it short:

I have a Rolex watch from the 80s that I have an offer for from an online watch buyer. I have no experience selling watches and want to avoid getting scammed. From all appearances this seller (watchbuyer.ca) seems on the up and up but I don't know enough about this world. Do any of you experienced folks have any advice? What can I do to protect myself?