As stated above the LG 27UD68 is a great 4K IPS monitor $400. I just bought an open box unit from Best Buy for $355 and love it. It is a great upgrade from my Dell 1080p. There isn't really any other 4K IPS monitor competing in that range. Next closes option would be the Dell P2715Q @ $480 on Amazon but beware that they have reported issues with the monitor getting stuck in sleep mode. Also, there are several TN panel 4K monitors under 400 but I just don't find them visually appealing.