$600 for a 24inch is reasonable
I paid around $500 at the time for my 22's EACH.
I plan on paying around $600 in £ (whatever that is this week haha!) for a PVA panel.
the IPS is great, but i do like play the odd game every now and again and the price for decent responce times (for gaming anyway) is pretty heafty on IPS.
PS. tell me what screen you buy! I've not quite got the money together yet to buy a screen since I'm just gonna use one of my current 22's at my studio and the other at home until I get enough money to go buy a good 24" for the studio.
First on my list is a colour calibrater
Canon EOS 5DmkII + BG-E6 + Canon EOS 40D + BG-E2N + Canon EOS 33
Canon 17-40 F/4L
USM + Canon 24-70 F/2.8L
USM + Canon 28mm F/1.8 USM + Canon 70-200 F/2.8L
USM IS + Canon 85mm F/1.8 USM
Canon Speedlite 580EX II + Canon Speedlite 540EZ + 2 x Nikon SB-80DX
Cactus V2s Wireless Trigger - 5 x
Cactus V2s Wireless Reciever