- 50 euros + ticket cost if you pay the controller right away or within 3 days at the ticket counter
- 100 euros + 5 euros ticket if you pay within 15 days at counter
- 200 euros + 5 euros ticket if you pay from 15 - 60 days at counter
I have no idea what would happen or not happen if you choose not to pay though, I personally hate living with this kind of burden and it was our mistake for not getting a ticket in the first place anyway.
Hope this is helpful for some. Book your tickets on trenitalia.com in advance if you can especially during peak travel season (Jul&Aug)