I know, I know, Ebay rape us with their own and their PayPal fees!
But I sell quite a bit on there, and twice in the last few months I’ve had customers pay and not add the postage, (I always say they can collect in person which is free)
Perhaps I think what’s going on is that they’ve worked out that we tend (I certainly do) is package stuff up at the end if the auction, stick an address label on it and once the paid email comes through drop it into the Post Office. I’ve now taken to checking each of those emails and the funds coming in as I got caught once and don’t want to get caught again!