Hmm, You might be spot-on at 10 mW. I haven't found typical values for current draw by touch screen type. I see an example capacitive panel for sale at http://olink.en.alibaba.com/product/...uch_Panel.html
Deep sleep state current draw: 0.2 μA typical
Low power state current draw 0.8 mA typical
Active state current draw (continuous finger tracking): 8 mA typical
I imagine IR touchscreens use more energy (enough to create and detect many criss-cross IR beams).