Shouldn't be to hard. You can even go 1080.http://www.newegg.com/Product/Product.aspx?Item=N82E16824254045
These are 23" screens for $179 shipped. Two should run $358 leaving you with $242 for a DP screen. Not sure how to find those on newegg.
If thats not enough for a DP monitor, then 1050 might be the way to go.http://www.newegg.com/Product/Product.aspx?Item=N82E16824236076
22" 1680x1050 screen for $160 shipped, but not the $15 rebate. Should be able to get two of them for $305, leaving you with $295 for the DP monitor.
If your system is beefy enough the first option is the way to go. Even if you had to buy the active DP to DVI converter you should be able to get those screens x3, and the converter for just over $600. Well worth it.