It doesn't really make much sense to factor them in for price per watch during it's production run, as it's always going to be changing with every watch made. And even high end watches are fairly high volume rolex alone makes over 1million a year.
Also just look at one model, then look at the gold version, usually there's a huge difference that's much higher than the volume of gold. (and considering the gold is much easier to machine) they do stick a huge profit on.
For example the fabs to produce a cpu cost something like $2+bn, but you wouldn't say that the first 100 cost 20 million each.