Just about everyone has a different opinion about which one is the "best" one. Just stick with the quality brands.
IMO, the words "DVD" and "resonably priced" shouldn't be used in the same sentence when talking about car audio.
Check the classifieds on some car audio forums such as
www.sounddomain.com or
www.elitecaraudio.com. E-bay is also a good place to look
-Josh, aka the tireburner