I hope no one is insane enough to buy this.
Yes, it's damn high, BUT with the shortage of cards everywhere, even THAT sort of price is starting to become "normal".

Several months ago, you could get a brand new RX 580 8GB, for ~$210 - $230, and now the only place that seems to have any, is Amazon, and when I looked a couple days ago, there weren't very many of them, and the cheapest one was ~$650!

The used market is simply following along with the current trend.