Apple U.S. offers only Japanese, French, Spanish, and English keyboards with their MacBooks. Here are a few possible solutions:
1. Buy an Italian MacBook Pro from eBay, OR
2. Use an English keyboard with an Italian layout, OR
3. You could do what I did, which is buy a MacBook Pro from the Apple website, and choose the French keyboard, then use an Italian layout with it. The French keyboard has the same number and physical layout of keys as the Italian keyboard, so with an Italian layout it will behave the same as an Italian keyboard. The only difference is that while the keys are positioned the same on the French keyboard and it has the same number of keys, the letters that appear on the keys are not all the same as the Italian keyboard. If you can type without looking, or if you can memorize which letters are on which keys, this will not matter if you have the layout set to Italian. Utilizing this same idea, if you'd like to be able to see the correct keys as you type, you can buy an Italian keyboard cover from KB Covers (search on Google) that will fit the French keyboard. So basically you'd have a French keyboard, but with a cover that goes over it which makes it basically like an Italian keyboard.