Mintek MDP-5860 5-Inch Portable DVD Player
VERY PLEASED
When I purchased the DVD player it was MUCH cheaper than any other product(although prices have come down since then).  It works with the battery, in your car lighter, and you can plug it into the wall. I purchased it for a plane trip with my 3 year old but it has worked well and he has yet to break it(and he is very good at breaking things)