One idea that you might want to consider is this: irrespective of the price, if you're buying the watch for yourself, then that's the only person you need to have a talk with...if you like the watch and can afford it, then that's all there is to it.
If you're buying the watch looking to either sell it ( one assumes at a profit...! ) or use it in trade, then you're in a profoundly different situation, and one that may have two, distinct components: one, where you're expecting a rather minimal profit and / or to trade for something about the same, and the other, where you hope to really do well, and walk away a Winner!
On a personal note, it seems to me that quite a few folks ask about watches that they intend to keep, and use themselves. They're not traders or running a business...they just like watches, and are wondering if the watch they're considering is 'real', and if the asking price seems OK. This is a 100% Good Idea, and hopefully will provide a bit of history of the watch and enhance the pleasure of owning it. It's a great idea.
Then again: if you're interested in living with the watch, well...it's your watch, and not the person or persons who are commenting on it. If you like it, get it and enjoy it. Whether it comes with an 'Certificate of Authenticity', signed and dated and sealed with a blob of red wax imprinted with an imposing Coat of Arms, or a tattered slip of paper from a local pawn shop, what's the difference?
Buy it / wear it / enjoy it...!