Here's the card:https://www.amazon.com/Sapphire-Radeon-GDDR5-DVI-D-Graphics/dp/B07MCDNQX2/@jitter77
pointed it out in this thread:https://forums.mmorpg.com/discussion/479096/amd-r9-270x-2gb-vs-rx-570#latest
I don't often start a new forum thread to highlight a particular deal, but this one is worth highlighting. Basically, Sapphire built a bunch of GPUs for mining, then cryptocurrency prices tanked. That probably means that they have a large number of cards that they need to sell to gamers, and that means big price discounts.
That the cards are built for mining does mean that they come with some drawbacks. For starters, the PCI Express connection is PCI-E 3.0 x8, not x16. For some (not most) compute purposes, that's a showstopper, but for gaming, it will rarely matter. It also has only one monitor port, and DVI at that. So no multi-monitor, no HDMI, and no DisplayPort. That's also a showstopper for some people.
But if those aren't a problem for you, then it's going to be years before you can get this level of performance in a brand new card for $100 again. And yes, the cards are new, so you know that they haven't just spent the last year mining around the clock. That's the life that they were intended for, but then people figured out that Ethereum isn't actually worth much, and so the miners didn't want them.