From reading various forums I understand that it is NOT advisable (financially speaking) to buy tickets online through raileurope.I also read that it is cheaper to buy up to 3 months ahead on a Europe based site such as bahn.de. However, when using the bahn.de site it states they don't sell out of country (out of Germany I presume) tickets over the internet. Do we need to wait until we arrive in Rome before buying tickets to Venice? Or is there another option?
If your talking about domestic Italian rail tickets, they can only be purchased in Italy once you arrive in the country. The Italian Rail website doesn't accept US credit/debit cards.
http://www.roninrome.com/%20transportation/buying-a-train-ticket
Thanks that helps a lot.
While you cannot book train tickets at bahn.de for trips totally outside of Germany, you can book by phoning the DB Call Center. Dial 011 (US international access code) + 44 (country code for Germany) + 8718 80 80 66. I haven't actually done this so I don't know if doing so can get you the same advance-purchase discount fares that are offered on the Trenitalia site.
However, waiting until you get to Rome will work just fine.