I have to be honest, I am 100% done selling cameras on ebay. After my last sale, the seller complained to me that the camera was "dusty", and they claimed it was because I used shredded paper as packing filler, and they wanted me to pay for the camera (which they paid $80 for) to have a CLA. I declined, and they left me negative feedback.
There's nothing I can do really except report the buyer to ebay for inappropriate feedback (or for requesting additional services, I guess?).
The topping is, I found out the seller is in Hong Kong (of course 9__ 9) but has a U.S. address. So despite not shipping to international buyers, and opting out of the mess of ebay's shipping program, somebody will find a way to screw it all up.
And it's only camera sales. I sell lots of different stuff on ebay, but camera buyers, particularly those overseas ALWAYS invent something to complain about. And it never happens with any other items. Unspecified "dust" seems to be a particularly common complaint. Sometimes it a lie, sometimes it's they just didn't read the description, I've had a few cameras which I plainly described as "dusty" provoke messages from their new owners, about how the camera is "dusty", as if this is somehow a surprise.