Escrow

Escrow is an arrangement where a third party holds the buyer's payment until the buyer has received and accepted the watch, and only then releases it to the seller.

Many marketplaces build escrow into their checkout, and independent escrow services exist for private deals. It protects both sides: the buyer isn't paying for a watch that never arrives, and the seller knows the money exists before shipping.

For large direct sales to buyers you don't know, escrow or another verifiable payment method reduces the risk of fraud.