Depends, i spent over a year of keeping an eye on ebay to find a set that didnt go to expensive. Ive seen some finish at over £120. (elise or VX220 ones)
But with an astra digidash, once its installed physically its plug and play, with the VX200/elise dials, its easy enough to get the warning lights and revs working, but speedo, fuel, temp etc will all require additional items to make work accurately. Which is bound to add cost.