I can attest to what OP @Iqet has said. I had travelled from Berlin to London very cheap in 2011 (I think under 20 Eur , because the whom I bought it from, secondhand, was sharing the group ticket as well). It was my first trip to Europe when I was a student in UK. And I had fallen sick, hospitalized (insurance took care of it), and I missed my flight back, as I was in hospital. I had no money to book a flight or a proper train ride back to UK. That is when one kind stranger helped find this ticket in a website which was only in German and gave me the ticket printout and instructions to board the train. It was literally a life saver.