Fifty-four days before takeoff is, on average, when domestic airline tickets are at their absolute lowest price. And if you don't hit 54 days on the head, you should usually book between 112 to 21 days before your trip within the prime booking window  for the lowest possible prices.

You may think you need a credit card to purchase an airline ticket. But a debit or prepaid card will work just as well. And your options may even expand to cash and checks if you book your flight through a travel agent or if you purchase your ticket at an airport ticket counter.