If you know your exact travel date, definitely go to the SBB site (also available in English) and buy a Supersaver ticket. I had a look of your Zurich-Brig trip and you can find Supersaver tickets for ~USD50 pp. These tickets are non-refundable and are delivered as a PDF printable at home. Supersaver tickets for your November trip will be available one month before the travel date. Price increase with the number of tickets already sold for a given train, so it is recommended to buy as soon as your travel date is confirmed.