If it is the bulb they are quite correct. Look sideways at the display, maybe with a torch and see if you can infact see the digits in the LCD although not backlit ! If so its for sure its the illumination bulb. As I remember this is not your standard cheapo filament bulb its a high brightness halogen lamp that illuminates most of the instruments. You have to remove the dash binnacle to get to the rear of the unit and this involves the removal of the trim and possibly the steering wheel (to make it easier) If you think of a garage rate of appx £40 hr plus the bulb its not far wrong as if you havent done this work before it would take significantly longer !
Of course the choice is yours. It would make good financial sense whilst the dash pod was out to replace all the popular illumination and warning lamps whilst in there.
Good Luck Steve
SB
November 2006