Hello Kailoiroo90
The cheapest ticket is the Saver Day Pass. Be sure to select the full price without Half Fare Travelcard if you don’t have this travelcard. You must buy it in advance as soon as possible and it is not refundable:
https://sbb-tickets.cc/en/tickets-offers/tickets/day-passes/saver-day-pass.html
You can search the timetable on sbb.ch or in the SBB Mobile app and choose a direct train from Zürich HB to Visp to avoid a change in Bern. You have currently replacement buses between Visp and Täsch due to construction works.
An example (check the timetable again before departure):
Kind regards
Danhiel