Q.Which is cheaper - buying tickets at the station or using this Service?
If you are using a reserved seat, this Service is cheaper than buying it at the station, but if you are using a non-reserved seat then the price is the same as the price at the station. Note that separate fares are required for any conventional lines you use to get to (or from) the Shinkansen station; so, depending on which boarding sections you use, it may be cheaper to make your purchase at the station.