This is a very, very, very hard to find item. And if you do find an original one in working order it will be a) very expensive and b) likely to become faulty within months.
They used to be available from MB for about £300 or so each. Not sure if they still do them now though?
mabz is referring to the 190 forum
Mercedes-190.co.uk
There was a guy from the US who joined up and was offering to replace the LCD screens, or sell repaired units - I think they were somewhere in the region of £200-300 or therabouts. A good effort but not 100% OEM - still most people wouldn't know
Will