We have an HP Compaq L2105tm 21.5" touchscreen in our main studio. I believe it was around $185 from Tiger Direct and we've had it since at least 2011. Occasionally it looses connectivity, but it is a very long run to the computer(about 25').
All you have to do to get it going again is disconnect a cable from the bottom of the monitor and then plug it back in. To clean it you just disconnect that same cable.
I don't use the touch feature much on air anymore because of a tremor I have that started causing me to double tap things. I used to find find it very useful when editing rotators but now find myself primarily using the mouse as I've gotten out of the habit of using the touchscreen. The touchscreen does come in handy when someone has inadvertently left it in manual and then walked off. No fumbling for a mouse, just hit the button on the screen. We did have an issue once where our office manager put a post it note on the top edge of the monitor. Overnight the corner of the post it note tapped a hot button about 4 dozen times triggering a short bit of audio. Overall I'd say I'm happy with our purchase.
On another note, we shy away from wireless mice and keyboards.