https://www.pcgamer.com/this-overclocked-radeon-rx-580-8gb-is-the-cheapest-around-at-dollar160/

Even though it's a little older this point, the Radeon RX 580 is still one of the best graphics cards, based on its ability to deliver excellent 1080p performance at a mainstream price. If that's the direction you're thinking of going, head over to Newegg—there you'll find an overclocked Asus Arez Dual Series Radeon RX 580 for $159.99 (after $20 mail-in-rebate).

That's the cheapest around for a Radeon RX 580 with 8GB of onboard memory. Even most 4GB variants cost more, save for Gigabyte's Aorus Radeon RX 580 4GB, which can be had for $149.99 after coupon (15DEALPC16) and MIR.