I paid 2100 RMB (about 330 USD) for my HKC 2560x1440 27" monitor. Supports HDMI, DisplayPort, DVI, VGA (to get those, means they splurged on a video scaler), has audio input, and was pixel perfect. Color rendition is surprisingly good, far better than I anticipated, but that is only eyeballing it and not using a colorimeter. Oh, and has wonderfully crappy 2W speakers if you are into torturing your ears more than your eyes.
There was a brand called Sekei available with a 50" 4K TV on NewEgg not that long ago for... about $900, I think it was? I forgot to save a link to it, unfortunately, and I can't locate them now. Pity. I did find a link to info about the panel, though. Would be fun if it could actually do 120 Hz at 4K res, that is only for 1080P or lower.