Dell S2817Q 28″ 4K Widescreen LCD Monitor for $299.99 shipped. Here is a screenshot for reference. It features a 3840 x 2160 (4k) resolution, and lots of input options, including 2 HDMI/MHL connectors, 1 DP connector, 1 mDP connector, 2 USB 3.0 downstream connectors, 1 USB 3.0 upstream connector, and 1 audio line-out port. Most places have it for about $470.
This deal has expired as the price has been raised. Congratulations to those able to get in on it.