Italy is a popular vacation destination but buying a prepaid SIM card can still get complicated for a tourist.
In Italy there are 4 network operators (TIM, Vodafone, Wind and 3 (Tre) ), which use european standard frequency bands. So (unlocked) smartphones bought in Europa should work with local prepaid SIM cards without problems.
To buy a prepaid SIM card you have to verify via passport. Buying cards online can be quite complicated for tourist and even in stores a further registration could be necessary.
Here you can find alternative options for an affordable online-trip to Italy: http://www.data-sim.info/en/international-prepaid-sim/italy/