fyi: You will be flamed.
There are many FAQ's avvailable that cover all of this.
http://www.digitalww.com/DWW-6500.htm) for $650
or you can get a motorized flip-out single din 7" unit like the following for $450 at the mp3car store or one just as good for about $250 from eBay new from HongKong...
or you can get a regular 7" screen for about $175-$220 on eBay or a huge amount from the mo3car store that you will need to fabricate yourself like this:
There is also another option for a "transflective" screen for about $680 from the mp3car store.
It is pretty hard to do it right, but easy to screw it up.