I bought the phillips model pet 9402 dual 9" screen unit last night and am taking it on a trip today. The power cord is really cheap, but other than that it plays nice and strap mounts to the head rest posts. You can find these on line for less than $150 (dual displays) and I figured it will work for now.
I just bought a 2011 SE Highlander and the salesman said do not buy the factory DVD entertainment system option. For hundreds of dollars less than the price of the factory unit you can get two Ipad's and snap them into a headrest mount. He had a Highlander customer go this route and his kids could not be happier.
http://blog.proclipusa.com/Blog/bid/...Headrest-Mount