I have one of those cheapo chinese double din gps units. I bought mine for about 250 before the android ones came available.

The bluetooth works good and it's very helpful.
The mp3 player sucks as it uses the DOS short name and not the full windows name (windows file system).
The apple control sucks.
Don't use the dvd player.
My video input failed to work as the camera did not work. Still working on that issue. Been busy with other car issues.
GPS is a mixed bag.

If you go that route try and get an android one first. I have this in my ebay watch list.
Double 2Din in Dash 7" Android 4 2 OS Car Stereo Radio iPod Bluetooth 1g 1080p | eBay

So my original map card died destroying my map gps software. So i had to buy an windows ce compatible map package. I like it. every once in a while, it looses it's settings and I have to reconfigure it. I am pretty happy with. My unit is really two computers that share the same audio and video. One for everything else and the other for the GPS. So again I would go android.