How do I buy an airline ticket if I do not have a credit cad?

I have always purchased airline tickets online through Orbitz or Travelocity, using my visa or MC. But soon I will cancel all my credit cards and be on a cash-only basis. Can I still buy an international airline ticket if I go to the ticket window and try to use cash to pay? Someone told me I will not be able to do this because the airlines will think I am some kind of terrorist. Should I get someone else to buy the overseas ticket for me with their credit card? Or can I go to the airport and just use cash to buy a ticket to Japan or Germany?