Yes, it is true, Switzerland is expensive. Perhaps not so much for people living in Switzerland, as wages are high and taxes are low, but for anyone coming from abroad, prices can initially be quite alarming. Though, admittedly, Stockholm is – depending on where you are coming from – not cheap either, and the difference between Sweden and Switzerland is not as big as Germany and Switzerland for example.
As with Stockholm, I would recommend anyone on a budget to keep track of their finances, make use of student discounts wherever possible and preferentially go to “cheaper” supermarkets such as Lidl and Aldi instead of Migros or Coop (comparable to Hemköp, ICA etc.). For orientation: I paid 495 CHF for accommodation per month, 29 CHF for my prepaid subscription, 62 CHF for my monthly public transport ticket and 350 CHF for food. In contrast to KI, ETH has many (more or less) great cafeterias and food options around campus. In my case, unfortunately only the Polyterrasse cafeteria was open at the main campus, but they offered a decent lunch for around 6 CHF. Keep in mind that, generally, a visit to the Kreisbüro will usually cost you some money. You will need to pay for the residence permit and if you need a confirmation for your deregistration before leaving Switzerland, you’ll have to pay again.
Thanks to the Swiss-European Mobility Programme (SEMP), I received a scholarship of 1900 CHF. I did receive the money in cash, though, and in order to be able to use it to pay my Swiss rent, among other reasons, I decided to open a Swiss bank account. I went with PostFinance who offer a free account for students. You could fill in all information online and receive the documents via mail, but it was necessary to visit a PostFinance office to open the account.
With the Swiss-European Mobility Programme (SEMP), you do not need to pay any tuition fees and you even get a ASVZ membership for free. They have an extensive offer of sports classes and gyms all over Zurich and are very popular. I was never able to use my membership due to the pandemic, but I would nevertheless highly recommend you to check out their offers.