It’s easy to buy tickets in Germany and easy to buy from the kiosks in Italy. The lines at the ticket counters were very long at Termini when we were there in September of 2004, so use the kiosks. I would try to buy tickets a day or so in advance, but I doubt the trains will be sold out, so you can probably buy as late as an hour before train time. The prices will be the same as buying from the national rail company websites ( www.trenitalia.com and http://reiseauskunft… ) and significantly less than buying from other sources.

However, I would check those sites to see if there are any low priced specials for the dates you want to travel, particularly if you’re taking overnight trains between Frankfurt and Italy. You may find some good deals for the tickets in Germany that will be sold out before you get to Europe. If you’re leaving directly from the Frankfurt airport train station and have a tight connection you might want to buy that ticket now.