Whether you are looking for a professional level display with 99% Adobe colour gamut or a large 1440p display (sorry not quite 4k) to game on, at $850 the Dell UltraSharp U2713H 27" IPS display is a great deal.  The USB 3.0 connectors are a nice touch but they do add to the size of the bezel for those with enough lucre to consider running more than one of these displays.

Dell UltraSharp U2713H 27" 2560 x 1440 IPS-panel LCD Monitor (Flagship 2013 Model)
Dell Home is offering 27-inch UltraSharp U2713H 27" 2560 x 1440 IPS-panel, LED-backlit LCD Monitor for $849.99 with FREE shipping. Use $150 instant savings to get final price.