Audiovox D1730 7-Inch Ultra Slim Portable DVD Player
Great Value but Fragile
We bought two of these for our 5 & 8 year old sons.  They are a life saver for travel.  They have a great picture and good battery life.  They include everything you need, even the DC adaptor for the car, which costs up to $... extra with other models.  The only downside is the hinge design is not made to withstand any more than very careful use.  Our 8 year old managed to break one of the hinges on his without really getting rough with it.  It still works fine and we have glued it.  Just be careful if younger kids are going to be using it.  Of course, for the low price, you can just get another one if it gets really torn up.  We bought two of these for less than one of some similar models we looked at.