I have the Dell ST220T, which I am using in conjunction with several 30" monitors. It has an IPS screen which allows use almost horizontally. It is under AU$400, but is only 1920x1080pixels at 21.5". Fortunately, its pixels are about the same size as those of the 30".
For my many observations using this monitor, see:
NextWindow make a multi-touch overlay for a 30" monitors (http://www.nextwindow.com/products/2700.html), but it costs half as much as the monitors and I think that it may make the touch surface several mm away from the LCD, which, when laying the monitor towards the horizontal (the only way to really use a touch screen without strain), may introduce parallax errors in positioning because of the low viewing angle.
Note that Win 7 allows only one multi-touch monitor as standard, and it must be the primary monitor.