Different version of an old tune. I’ve encountered this a couple of times although never with so much back and forth. At least the scammer had to work a bit. Common denominator in these scams is low price and urgency in closing transaction. My latest version was dire need for funds hence the cheap price and leaving to work on offshore oil rig and need to close before leaving. A friend of mine was also nearly scammed by a very realistic looking eBay listing.
I used to get this response every time I advertised for a spare part......so gave up advertising for spare parts, except on closed Facebook or niche sites.