: If you sell, you have about the same problems!
: Who guarantees you will finally collect your
: money, or the return of your watch?

It seems to me that as the seller... You can dictate terms. For example, a USPS Money Order is the same as cash, so when you receive it, you can go immediately to the Post Office present it to the clerk and they pay you cash. So, you can specify payment in USPS Money Order(s) (the USPS has a $1,000 limit on a single MO)...

You insist on sending the watch properly insured, that way if it is lost or damaged in shipment, you or the seller are reimbursed.

As for returns, describe the item for sale exceedingly accurately, document it, and state no returns except for error in description(s)...

If you list it properly and cover your behind you should be ok.

-- Chuck