You want a headset that actually cancels noise, fits comfortably for hours, and holds a charge through a cross-country flight. Buy a solid pair once so you are not replacing a peeling, cheap headband or dying battery in twelve months.
Late autumn holiday shopping weeks are the sweet spot because older models drop in price right when new versions hit the shelves. Last year's flagship audio gear usually sounds just as good as the brand-new release, but costs a lot less.
The 0% intro APR for 15 months is a deadline, not free money. If you still have a balance left when those 15 months are up, interest charges will kick in on whatever you owe.