Build a range first
Use several relevant comparables and adjust for reference, location, condition, accessories and seller quality. One stale listing is not a market price.
Name the adjustment
Missing links, deferred service, polished geometry or a weak return policy are reasons for a different number. State the material issue briefly instead of attacking the watch.
Offer a clean transaction
A clear payment method, realistic timing and few unnecessary conditions can make a slightly lower offer more attractive. Certainty has economic value to the seller.
Avoid false precision
An offer can be specific without pretending the market is exact. Leave room for uncertainty and know the highest landed cost that still makes the watch a good purchase.
Be willing to lose the listing
The strongest negotiating position is a valid alternative. If the deal works only after abandoning your range or service reserve, the correct result is no transaction.