For the iPhone there are specific options, but if yours are locked you cannot use an Italian sim-card.
CoopVoce is a virtual operator and you cannot find their offers at TIM shops. You can find them at bigger COOP supermarkets, but I fear it won't be available to non Italian residents (you need to be affiliated to the COOP). Noverca has a per KB billed option, but it's web-based only (or at San Paolo banks).
I'm going to correct the typos, thanks!
