eBay has the Dell 27" S2716DGR 2560x1440 144Hz GSync Gaming Monitor for $370 with free shipping. Features 2560 x 1440 resolution with 16:9 aspect ratio, Ultrafast 1 ms response time, 144Hz refresh rate, HDMI and DisplayPort inputs.
Best Buy sells it for the same price.
Amazon has the LG 34" 21:9 UltraWide IPS LED LCD Display (34UM88-P) for $185 with free shipping. List price: $800. It features a 3440x1440 native resolution, displayport, and two HDMI inputs.
Has good Amazon Reviews.