Guys, why don't you read all the pages I wrote about the subject before asking FAQs?
Here are all the offers (with activation cost):
PrePaidGSM: Italy
Here is the complete overview for data (including coverage maps):
PrePaidGSM: Prepaid Data in Italy
You can buy a simcard anywhere in Italy, it's really easy, there's plenty of shops in every town. If you go out of Italy there are
other operators with other offers.