Here's the touch screen news.
Good news: you do not have to replace the whole nav / radio / cd unit for $3600 just because your touch screen is cracked. The replacement screen is $22.19!
Bad news: the replacement screen is tricky to fit.
Touch screen is made by Clarion. Clarion Part number Qy7200Na
I purchased my replacement touch screen from PacParts, Inc (http://www.pacparts.com
) who were very slick and easy to deal with, and I highly recommend them. Price was $22.19.
PacParts phone number is 800 421 5080 or 310 515 0207.
If your actual LCD screen (under the touch screen) is damaged, a replacement part is also available from PacParts. SKU: 9300467159977, $152.36.
You need a #2 Philips screwdriver to get the nav. unit out of the dash, and a #0 Philips to dismantle the screen bezel to replace the touch screen. *BUT*, as the touch screen is tricky to fit, most people would probably be better off having the touch screen replaced at a Clarion service center. Service centers can be found under the support tab on http://www.clarion.com
, then click on "service" http://www.clarion.com/us/en/support/service/index.html
I hope this information is found by those unfortunate enough to have broken their touch screen before they fall into despair and spend the $3,600 for a new box from Nissan.