For something high quality you're going to be staring at the entire time you're using your computer over the next five or six years, $600 is more than reasonable. I've spent over $1,000 on a monitor before due to the desktop size demand. $1,000 was actually on the lower-end for the ones in the class.
Sure, you can pump more money into a set of flagship cards, but you'll never tap into they're potential just running at 1080. The larger you go with screen size at a given resolution, you're going to see a decrease in pixel density. Your viewing distance being a prime factor.
Example; Take a 1080 output, blow it up to 130", then stand four feet away from it. Horrible quality. Not as noticeable with "27-32" monitors, but if you're buying expensive video cards to play games at high quality, it should obviously be a priority.
Take your savings from buying two 970s instead of two 980s, add on $200, and there's your 4k monitor.