I bought a 52mm-52mm coupler from a HK supplier (goes by the name of william-s-home). After I paid for the item, I noticed that the seller had a warning that the shipping could take 20-30 days and to email them if I wanted to cancel because I was just reading this note.
I emailed him and requested a cancellation. The seller was SO polite. We had a few exchanges and he/she was always extremely respectful.
I now have this image in my head of a venerable old Chinese trader who takes his business and reputation very seriously. For him, this is not just a way to earn money. It is a way of life, a principle, and things must be done correctly. The item cost $4.00 with shipping. It probably cost more than that for both of us in terms of the time spent emailing and completing the formalities for cancelling the transaction.
It was all very civilized and suddenly made me want to be a global trader, exchanging emails with people from far flung places in the globe, because life is too short and the world is too big and there are too many good people out there to not get to know them.