To buy an e-bus today you can expect to pay around $1,000,000, as compared to $750,000 or so for a diesel bus, or about 30-40% more, but over the life of the bus, e-buses are about 25% cheaper due to the reduced operating costs.
Today, the total cost of ownership of electric buses is lower that diesel, hybrid and compressed natural gas powered buses.
By 2030, Bloomberg is expecting e-buses to reach price parity with diesel buses as battery costs fall. If e-bus adoption accelerates, price parity could happen by the mid 2020s.