Doesn't take much to go on my list of buyers I never want to deal with again. Today the buyer purchased something and then tried to negotiate for a partial refund. So they are blocked and reported to ebay for attempting to extort us as they said "if you don't give me a lower price or cancel the order I'll leave bad feedback". They will likely be banned from ebay as that is one of the fewer things they actually don't accept.
People really can be asshats sometimes. If you want a lower price ask before buying, not after.