This happened to me, payed $110 for a ski jacket, get an amazon box and lookup the price on amazon - $80. I had to applaud the eBay seller for their hustle..

It’s a money laundering thing too.

There was a story in my area a few years ago where people had some sort of scheme to convert Amazon gift cards into cash via EBay.

I stumbled across an anonymous payment processor that accepts all kinds of shady business, like online casinos and escorts. They accept payment via gift cards to Amazon and elsewhere. Maybe this is how they convert that into cash. I was puzzled about how that would work.

This arbitrage is also good for the buyer, if they don't have an Amazon Prime account.