What resolution do you want? SRGB or RGB? I bought a 4K monitor a little over a year ago and discovered that a lot of my software was not ready for it, so I returned it. Things have changed since then.
I think that a monitor with hardware calibration would be my choice, here are some reviews that are pretty knowledgeable.
Reviews and product information for BenQ products, monitors and displays
www.northlight-images.co.uk
The BenQ SW271 is a solid pick in your price range for a 4k 27 inch monitor.
For a 2K Monitor, check out the BenQ SW270C
Both monitors are 100% Adobe RGB. If you don't have a monitor calibration tool, plan on getting one if color accuracy is needed.