I'm looking for a monitor that is at least 27" and is under $400. I prefer 2ms response time, but I'm still open to 5ms if ghosting isn't a problem. My old 5ms 24.5" Samsung had really bad ghosting problems when the game was in low light areas (Bioshock ).
The best at that price point would be one of the South Korean monitor brands sold on ebay. They use the highest quality screens at less than half the typical cost of a retina display. Something like this:
This is an AH-IPS (best color reproduction, 178º view angle) 27" monitor, with HDMI and DVI, and a resolution of 2560x1440 (about 78% more pixels than full hd, exaclty four times 720p).
Response time is 6ms, but never heard of ghosting in one of these. Keep in mind that there are no IPS monitors that ship running over 60Hz. IPS panels offers way better color, but can't switch as fast as TFT. (TFT has been around since the early nineties, AH-IPS was patented in 2011 an has only recently reached volume production).
If you rather not deal with international shipping and prefer to go with a more conventional seller, I'd recommend this: