The usual one is the CDR500 and you should find plenty on eBay. They use the eye level display in the car and don't have their own display. Make sure that it has the code with it and is described as being in first class condition.
An example:
http://www.ebay.co.uk/itm/VAUXHALL-VDO-CDR500-CD-PLAYER-CDR-500-/260835775655?pt=UK_Audio_TV_Electronics_In_Car_Entertainment_GPS_In_Car_Audio_Players_PP&hash=item3cbb0614a7
A nice alternative, in my opinion, if you can find one is the Philips DC614 RDS Car Radio CD Player, but they are quite rare now.
ChicksFan, August 2011