i just dealt with a buyer who i think must literally be insane. like bipolar, anger issues, something mental. from here on out insane buyer will be referred to as "B."
B bought used $130 item, and I shipped it almost immediately. after item is shipped, B sends worried e-mail, asking specific Qs about condition of item (red flag). B lives completely cross country, and bought standard shipping. After 1 week, B emails me complaining and making threats... going to report me to Amazon, wants $ back, etc. because he'd "never waited that long for an item to arrive, etc." i call PO, PO says package "guaranteed" to arrive on XX day - i forward message to B.
day rolls around, package does not get to B, instead I GET THE PACKAGE with a return notice/sticker from the PO that says "REFUSED" (!!!!!) i forward info to B. if it is possible to communicate a heart attack through an e-mail, B does this. literally screaming at me for being so stupid and using the USPS, "i chose the carrier, so it is my fault", blah blah blah, etc. and that "he did not refuse package" (B lives in apartment complex)
note: it is very clear that B is unemployed, and i get the sense that he is on welfare (which he has hinted at) - i wouldn't comment on this, but B is buying frivolous items for $130+ and behaving this way towards actual people trying to make a living - kind of irellevent to my question, but just want to paint a picture of the type of guy B seems to be.
I say i will re-ship & refund his original shipping charges (now about to pay double what was already higher priced shipping than amazon charged) using whatever carrier he thinks i should use. i say i will check into the fastest deals etc, and will try to get it back out by end of day and get back to him w/ tracking #. i was not able to get out of the house in time to do this. since i was not able to get tracking # etc, i did not think there was any point in messaging - planned to mail package/message first thing in AM. YES, I did NOT get back to him that night. Perhaps I should have, but I felt it was pointless to do so, as any remotely normal person would have probably gotten the idea.
by morning B has sent me 5 more angry e-mails. I'm "blowing him off" he's "going to report me to amazon" "going to file a claim" "you can explain to amazon why you are blowing off a customer" "going to report me to the Better Business Bureau" " the worst seller he's ever dealt with" "he has been SO patient this whole time" "he is a great customer" mocks me/what i've said in emails, etc… FIVE e-mails worth of this…
also says in the e-mails that if i have not yet sent item to "forget about it" and give him a refund. he then changes his mind 5 mins later, and say he will give me one more chance, if i get it to him by 5pm "tomorrow" that will be fine - if not, he wants a refund. overnight shipping would cost over $100.
So i issue a refund.
B is then super pissed that I issued refund. "he really wanted item"
oh yea, and i even researched on CL (FOR HIM!! cause i'm a pussy) and found the same thing in (what looked like) the same condition for even cheaper - only a few miles from where he lives.
"he doesn't want someone else's" 'he want the one i'm selling" "now he can't get what he wanted" etc…
so… i'm leaving out a whole bunch of details, but the cumulative messages he sent were all just so crazy and harassing and cruel. he was clearly trying to take advantage of a small seller cause he knew he could. NO business would have responded like i did and would have tried to accommodate him like i did.
now… i don't think i really handled this correctly (i think i was overly accommodating and too much of a push over)… but wtf should i have done? how do you deal with a legitimate crazy person? i don't know… 
in general, how should you deal with a legitimately crazy buyer? think i just failed. 
