That certainly varies. In our case, at that time, approximately 15,000 EUR plus connection costs were quoted for about 15 m over private land. However, the ground is also quite rocky.
It must be said that we are supposed to pay the full purchase price for the driveway and then feel a bit disadvantaged compared to the other landowners without a private road.
As I said, objectively complete nonsense. But nowadays sellers can simply impose anything on buyers.