I just found this looking around. It is GM part #19203053. This dealer is offering the Passenger Side DVD headrest player for $491.40 for the Titanium Cloth Interior. That's like a $500.00 price drop. The kit comes with a passenger side head restraint complete with DVD player / monitor, and a driver’s side head restraint “shell” excluding the electronics.
You can add a Driver side player for $364.00 or just the monitor for $218.40.
Please see part number 19155663 for the driver side monitor upgrade or part number 19157118 for the Driver Side DVD player upgrade. It looks like the Titanium Cloth is the only one on sale.

http://www.gmpartsdirect.com/results.cfm?singlepart=1&AddPartNumber=19203053&partnumber=19203053

I am not selling this system and not affiliated with this dealer in any way! I simply saw it and wanted to pass it along. :)