Okay, doing a quick search on WhichBudget, I came up with a one-way flight from Amsterdam to Rome in the middle/end of July (no idea when your trip is-- dates will help
) for 90 euros including tax.
It may be easier for you to go from La Spezia to a larger city in Italy-- Venice, maybe, since it's on the way to Slovenia?-- and catch a train from there to wherever you want to go. That's the best advice I can offer. But also check out http://www.bahn.de
for train information throughout Europe. Click "Internat. Guests" at the top right.