One thing to consider with IPS though, is that nearly all the screens use an anti-glare coating, which may or may not be to your liking. The Apple displays are one of the only IPS lines with glossy screens (colours 'pop' a bit more) I can think of, although what you gain in colour, you lose in reflections if you have a light source hitting the screen. This is part of the reason I got a Mac Mini and the HP, rather than the 21.5" iMac, since the layout of my room means where I have to have the computer isn't ideal for light, and also it worked out cheaper and is a bigger display.
I think there's a Viewsonic VA panel that's in your price bracket, with it's main drawbacks being handling very fast motion, particularly in FPS, and quality control being a little hit and miss in terms of backlight bleed e.t.c. (although you could return it). 2nd hand will also get you some bargins, although obviously you don't get any kind of warranty.
As for cases, there's quite a few with dust filters these days. Do you need the size of the XL over the regular R3? I seem to remember the latter getting more favourable reviews.