You have to reach Pirwdai bus stop by cab i guess because both the hiace and the coaster only get ready to move when they are all filled up... they don,t stop at random points ...
I don,t really know about cab fare and frankly speaking i doubt if some taxi driver is willing to go to balakot from ibd... most of them prefer to stay with in city and 1/10 drivers only move outside city here... anyhow you can go via whatever transport suits you 