My daughter will be on a college tour that ends in Florence. She and 2 friends want to travel to Interlaken by train. They will buy Swiss rail passes for their time in Switzerland but need to get over the border before they can use those.
She has struggled to find the cheapest way to get from Florence to Brig or Zermatt by train.
ANy help would be appreciated.
The "cheapest" way would be to take regional trains from Florence to Dommodosola. You would do this by buying the following tickets from Trenitalia or at the train station in Italy: Florence/Milan and Milan/Domodossola. It's a 5.0hr run and less expensive than the Eurostars. The regional train fares are about 50% less than the Eurostars.
Next, although Domodosola in well inside Italy, I believe that the Swiss may recognize this location on their Swiss passes or cards if you are traveling into Switzerland. I know they recognize Domodossla on a run from Brig to Lugano as it's the transfer point. If not, you can buy this ticket from www.sbb.ch. You can email them to see if a Swiss pass will work on this run. The runs do route through Brig.
I am not sure what you mean by cheapest way. You just buy the cheapest ticket available. If she is lucky she might be able to get the Amica fare (20% discount) on the Italian leg by buying a few days in advance. The Italian trains are pretty reasonable.