I was searching eBay for 4K monitors and saw this certified manufacturer refurbished Acer CB280HK. Looks decent for the price and would be a good alternative to the Korean 28" 4k monitors that are around $270~300. All of these comparable 4K monitors in this price range are TN panels.

Sold by the official Acer Recertified Store
90-day warranty
Link [ebay.com]

Specifications
Backlight Technology:LED
Brightness:300 Nit
Color:Black
Picture-in-picture, picture-by-picture
Color Supported:16.7 Million Colors
Contrast Ratio:100,000,000:1
Depth with Stand:9.63"
Display Screen Technology:Twisted Nematic Film (TN Film)
DVI:Yes
DVI-F INPUT:Yes
HDMI:Yes
Green Compliance Certificate:TCO Certified Displays 6.0
Maximum Resolution:3840 x 2160
Operating System:0
Processor Speed:60 Hz
Response Time:1 ms
Screen Mode:4K UHD
Screen Resolution:3840 X 2160
Screen Size:28"
Speakers:Yes
Width with Stand:25.93
ITEMWEIGHT:22.65
ITEMWIDTH:25.90
ITEMLENGTH:2.50
ITEMHEIGHT:15.00