I bought a $350 laptop off ebay with a DVD player, a small 70W inverter that plugs into the lights from ebay for $17, I have a piece of Velco (the stiff part) on the bottom of the laptop ($1) got some external speakers for the laptop for $15...yes...off ebay.
The thing sits on the middle 2nd row seat (folded down) doesn't move, has a 13" screen, great sound all for less than $400.00. It also sits perfectly on the console but I cannot open it.
Keeps all 4 kids glued to it during those long trips to Hilo. (2 hours one way)
Best part...I'm using it now to type this on the internet.
Think multi-function.