Pre-booked hotels are no longer available.
Public transportation in Zurich is usually efficient and punctual, so a budget accommodation outside Zurich Center may be a good option, if it is close to one of the train stations or along the routes of trams 6, 9 or 10.
See here a list of hostels and other accommodation options in Zurich. Check also airbnb. Something else that works surprisingly often is to ask if there are any free rooms for the week on facebook groups like this one. You may also try to coordinate your booking via the APMP Facebook group.