You have tons of options these days....
We got a flight sim for our store and the HP monitor has DVI, VGA, and HDMI so you can hook up a modern game console (and has internal speakers that you can feed audio through the HDMI) as well as hook up newer and older computers - go to town!
The HP 23" is nice (1920x1080, 16:9) and I think we got it on sale for $199...
A 24" should be only slightly more.