[landyacht]

The best thing to do would've been to get the one with the DVD package alread in it, and then just get an aftermarket screen.

Since that's not the case, i'd visit the dealership's parts department first and just see if there's anything they suggest. The only reason i say this is they may be able to give you tips on things to stay away from that could end up effecting your warranty.

After that, i'd just start calling stereo shops, the bigger named places to see what they have that would work, and start getting some price quotes.

Then you can check out the smaller privately owned places, tell them you've found X DVD player for your Expedition, and you've been quoted X to have it installed. Find out if they'd do a better price for you.

Hope this helps!