The Tech Report points out that 4K LCD displays don't have to be ultra-expensive. Philips for example has been selling its UltraClear 288P6LJEB for $599.99 since June 15.
This 28" LCD display has a TN panel with support for 1.07 billion colors, 3840 x 2160 pixels resolution, 300 nits brightness, contrast ratio of 1,000:1 and a response time of 1ms.
Overall the specifications look very decent, the only unknown is the quality of the TN panel.
In any case, it's 28" 4K monitor for 600 bucks. And it's not some barebones model, either. The UltraClear 288P6LJEB has an adjustable stand that can pivot into portait mode. There's a four-port USB hub onboard; two ports run at Gen3 speeds, and one has a fast charging mode. You also get a range of video inputs: DisplayPort 1.2, MHL-HDMI, dual-link DVI, and even old-school VGA. Even picture-in-picture and side-by-side input modes are included.
The display is based on a TN panel that's supposed to deliver more than a billion colors. I suspect the panel is similar to the one in the Asus PB287Q Scott reviewed recently. That monitor has excellent color reproduction, so I wouldn't dismiss the Philips due to its TN credentials alone.