I know this is a little out of your budget, but the absolute best monitor (that has ever been made to this day) is coming out soon at a price point of about $800.
Asus PG279Q has 144Hz (can be overclocked to 165Hz with a Nvidia GTX 9XX card), IPS panel and works with G-Sync.
Now, you might ask, why is this good?
Prior to this, you always had to make a compromise.
If you wanted 1440p, you were stuck with 60Hz, but still have the option of an IPS panel.
If you wanted 120Hz or 144Hz, you were stuck with a crappy TN panel, and horrible colours.
This is the first time in history that we are offered a monitor that lets you have your cake and eat it too.
Great image quality, colours, and super smooth/fast fluidity that will make gaming, movie watching, and almost everything look great.
I was fortunate enough to have seen it in person when I was in Japan earlier this year, and was very impressed.