
Unlike bullion, the value of scrap gold objects is 10-20% below spot.
In the case of the P1 the non-gold weight is within the fluctuation.
Secondly, the gold value is totally irrelevant since the watch has collectable value far beyond the cash scrap value.
So much more than any foreseeable value increase of gold to make that irrelevant too.
The P1 is a collectable object disconnected from it´s material value.
If you intend to keep it, simply enjoy it for what it is and forget the gold contents.
If you intend to sell it; put it for sale with a reserve yoú feel comfortable with. Again forget about the gold contents.
Because of the relatively high vaue, better not sell through ebay as the %s of ebay/paypal amount to several ordinary mortal´s LED watches worth

You and the buyer can both be off better through the sales corner of a watch forum.
Just put it on several so it will pop up on deal seeker and you will reach the same serious collectors as you would on ebay without the costs.
Good luck.