LG has aimed its latest 27-inch 4K monitor primarily at professionals who want a colour accurate monitor. However, the monitor should be suitable for some gaming on the side too, thanks to the tearing and input lag reduction technologies that it supports. The LG 27UP850 retails for US$549.99.
https://www.notebookcheck.net/LG-27UP850-A-27-inch-and-colour-accurate-4K-monitor-with-surprising-gaming-features.529019.0.html