I think you mean St. MORITZ (?). The Glacier Express requires a reservation fee in addition to your ticket. Search for Glacier Express Reservation, Sept. is still considered “high” season, so the reservation fee is higher, the earlier you reserve the better your chance of finding seats.
But, you can ride the same route on “normal” trains without any reservation fee, you will have to change trains in Brig, Andermatt and Diesentis.