Since you say you are not tech savvy, the best bet is to buy a cheap phone in Italy. This way, you are sure it will work in Italy. If you buy one from EBay and it doesn't work in Italy, you're stuck.
Just go into a phone store and buy one. TIM, Vodaphone, 3, and Wind are the major carriers with stores all over the major cities. Just randomly, I went to the TIM website and asked to see inexpensive phones, and it showed three different models (all basic "dumbphones") for a bit under €30. To this you would have to add a plan for minutes/texts (these inexpensive phones don't have data, just talk and text). Which plan would be best will be determined by how much you intend to use the phone.
You will need your passport to to set up phone service in Italy. You may also need a Codice Fiscale, so it's best to have one. On the bottom of this page are directions for getting one; print the CF out and take it with you, just in case: http://www.prepaidgsm.net/en/italy.php