So a year or so ago I got a Yamakasi M280PU Perfect Pixel, which is a 4K monitor. Thing is, it's only $300 (US). It felt really sketchy buying something from a company I've never heard of before, but I was surprised that it actually worked. Here are the specs:
4K UHD 3840 x 2160
60 Hz
28"
3 HDMI Ports
1 DisplayPort
Picture in picture
Picture by picture
TN panel
Some other stuff...
It is worth noting that in order to get 60 Hz in 4K, you must use the DP. HDMI at 4K is limited at 30 HZ. Also, the monitor setting menu will disappear after 15 seconds if you press the menu button, so you have to be fast in changing your settings. The stand is a little bit wobbly, but it does the job. It does have a VESA mount if you want something more sturdy. The backlight bleed is actually not bad, and I haven't had any dead pixels.
My only true complaint about this monitor is the stand: The bottom of the stand will leave highlighter-yellow circles on your desk, but they can be easily removed using a wet paper towel.
Two months ago, I purchased 3 more of these for my racing setup, and the cost of the three monitors together was about the same if you were to get one name-brand (Samsung or whatever) 4K monitor.
Sure, they might not be your MasterRace UltraWide Curved Monitors, but in reality, having a triple 4K monitor setup at the same price as a single 4K monitor is a real win.