Get a Dell U2413 Monitor for less than $500
A powerful computer requires an epic monitor to support it's capabilities. From the wide range of screens between 720p to 4K, I'd recommend finding a perfect medium such as the 1200p Dell UltraSharp U2413 monitor. Originally retailing at $729, you can currently buy this for only $490.30 and it's a blast to have. It comes with quite a few ports on the side for any kind of wire including the old VGA adapters, HDMI cables, and mini-HDMI. This is from eBay though and you can get yet another $20 from Ebay using the coupon. That said, this deal ends on the 22nd of January so I recommend you to get it as soon as you can.