If your children are younger and you will use it daily it will be better to have one professionally installed. If you will only use it for longer trips I would get a portable one.
I probably wouldn't have the dealer do it. I'd do some research and look at more "local type" shops and price out installation.
We are getting a new mini van. We are deciding to have them install a DVD system which is kind of expensive, or should we try a store like best buy to do it. What would you do, or have you had one insalled in the past.
Thanks
Of course the down-side is that you have to charge those, so I can see why you'd want the installed one if you'll be using more often.


) and paid less than half the price the dealer wanted. So, we got a better system for a lot less money. Ours is the kind that has the drop down screen, it also has inputs so we can take video games and hook them up if we wanted to, we got wireless headphones or we can put the sound through the car speakers. Definitely don't go to through the dealer and I probably wouldn't go through Best Buy either, find a car stereo store in your area and use them, they are better equipped and will have better gear. 
I paid $140 for one on Ebay. It included the FM radio feature, 2 wireless headphones, and a game remote (one game DVD too). It did come from China and had a Sony DVD Player in it (They are still being sold now on Ebay). It's the drop down one from the car ceiling - 9inches. I then paid $110 to have someone from American Furniture & Electronics put it in ($80 without the FM feature). That was in June 2010. It still works PERFECTLY. Amazon has them too (plenty under $150). Walmart even has one for $99. My co-worker just purchased one from Walmart. She loves it. She just had to purchase wireless headphones which are $10 from Walmart too. Make sure you get one with wireless earphones (capabilities - ie: IR/FM Transmitters).
When I purchased the car the dealer quoted me $1100 for a 7" one.
Walmart 7" overhead one
http://www.walmart.com/ip/DP-Video-7-Widescreen-Overhead-Monitor-with-DVD-Player-and-IR-FM-Transmitters-DZ733D/16775720
