I am arriving in Frankfurt by plane next Friday morning, and would like to immediately head to Berlin. I was wondering if anyone has experience with this route, and if there is a recommended approach to purchasing a ticket. Refunadable tickets on raileurope.com look very expensive. Would I have trouble or would it be significantly more expensive to just buy a ticket when I land? Any risk of trains selling out? Looking at today or tomorrow, it looks like tickets are all still available. Any insight would be much appreciated. I don't speak German, but I assume I'll get by fine with English, as I have in other Western European countries previously.
Thanks