The seller, roughly 20 minutes after the original posting on this forum, messaged me to tell me that he erroneously priced the watch at $1800 when he meant to list it for $4800. Before I had the opportunity to protest, he cancelled the transaction and refunded the $1800, thus removing any ability I may have had to pressure him or contest what he was trying to do.

We exchanged emails thereafter, but English is not his first language, and he's unaware of the rules that govern eBay and PayPal, so I was at a complete loss to resolve the matter. He's clearly speaking with others and I have no doubt that my purchase was cancelled due to intervening forces.