ASUS Radeon RX 580 O4G Dual-fan OC Edition GDDR5 DP HDMI DVI VR Ready AMD Graphics Card (DUAL-RX580-O4G) for $249.99 in-stock 9/30/17.
This is the current cheapest RX 580 4GB in-stock, but I have seen a MSI version for $230 yesterday with a poor quality heat sink which out of stock now. Buy it soon if you are interested as these usually last a couple hours or less before they sell out.
https://www.amazon.com/gp/product/B071CMPRZZ
Add some free popcorn and vitamins while you order too, if you have not done these freebies yet.
https://www.amazon.com/b?tag=slic…71
https://www.amazon.com/gp/browse….91297