sell quite a lot on e bay so far I have been ripped several time amounting to quite a few £100
It is normally people from abroad they think you can’t get at them.
Most common one is they ask you to send to an address that is not the one they have listed, and then say they never got it, you are then going to have to prove they asked you to send to that address.
They always contact you outside e bay and E Bay / Pay pal are just great at not believing you and believing the buyer.