I am going to assume you don't care too much about IPS vs TN and refresh rate can be capped at 60hz for 60fps gaming and that you also don't care much about latency either and that you aren't looking at anything that has Display Port inputs.
Or perhaps you know all of these things and just didn't want to share but that's cool.
Here is a list of monitors going from cheapest to most expensive with a 1440p resolution:
http://pcpartpicker.com/products/monitor/#r=256001440&sort=a8&page=1