Bugger stations have a ticket office, others have a newsstand. Tickets can usually be bought in bars and tobacco shops.
Recently they got a new app. It will generate a qr code, but in my expirience qr readers at the gates don't work that well. https://play.google.com/store/apps/details?id=net.pluservice.unicoc
The best zones to find a cheap room (imho) are:
Here a small map with different price range, I don't know the exact prices because I'm not a student, if you wanna know more about rents, I suggest to search via facebook or google for student's group (reddit is not popular in Italy)
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> How's life expenses btw? I'm asking for a month, without the rent
This heavly depends from your needs. Food, public transport and drinks are cheap, the nightlife not.
If you need some specific price please let me know, these are the average prices in the city.