I bought JapanNext's 4K display. I connected with MacBook Pro 2014.
I was using MacBook Pro like this.
I put the 4K display like this.
I couldn't let the 4K display output 60Hz. I struggled it, but I found that MacBook Pro 2014 can't output 4K@60Hz but 4K@30Hz. But I could output like retina display with my setting.
I liked this display though this display had a little downside. For example, sticky tape was on the logo on front panel, and the display's body is shaken when the display's button is pushed.
The display is 41,444yen at Amazon.co.jp.