They have machines in baggage claim selling tickets and "clip cards" and probably the daily and multi-day tickets. (I once bought a 24 hour card and it was a small clip card with one "clip".) The machines and the ticket counter outside customs can be very crowded.
One frustration for me is that the machines don't respond when you try feed banknotes. I typically have lots of cash in DK that I want to use. I had no problem in 2012. The machines do take CCs but you need a pin. They need to get help from the Japanese for machines that accept banknotes.
The machines in other stations and the metro only accept coins and CCs.