Haven't been in the loop for a while, but several years ago a buddy of mine was looking for an IPS monitor. He does graphic design work so it color quality was important to him. Both of us did some research and he ended up with a Dell.
They have a 23" for $299, but the resolution is 1080. http://accessories.us.dell.com/sna/p...n&sku=320-2807
They also have a 24", which has the 1200 resolution you are looking for, and it is $329. http://accessories.us.dell.com/sna/p...n&sku=320-2676
Both are height adjustable and have portrait and landscape mode, and reviews seem to be pretty good.
I'm sure you've come across this list, but it is of IPS monitors available now: http://www.pchardwarehelp.com/guides/s-ips-lcd-list.php