The electrification of public bus fleets is a central step toward a sustainable transport system. As electric buses replace diesel vehicles, charging demand introduces new technical and economic challenges. Previous research has primarily focused on the potential for adjusting e-bus charging schedules to maintain high technical grid performance, such as avoiding high power flows or reducing congestion at the circuit level. These studies highlight the potential for charging strategies to support grid stability, but their primary emphasis is on technical feasibility rather than operator costs. This study shifts the perspective to the economic dimension, examining how national and local electricity tariffs influence the cost of electric bus charging. We focus on a cluster of nine municipalities in the Västra Götaland region of Sweden, located in the SE3 electricity bidding area. Wholesale prices in Sweden vary dynamically by hour, while local distribution system operators (DSOs) apply relatively static but diverse grid tariffs. These differences shape incentives for when and where buses should charge.