A solid pair of noise-canceling headphones should last you at least three to four years of heavy travel. Buy a quality set now so you aren't replacing cheap, broken plastic every single season.
Tech companies refresh these models every year, but the features rarely change enough to justify full price. Look for last year's flagship model during mid-summer sales when retailers clear shelf space for the newest arrivals.
The 0% intro APR is not free money; it is a deadline. If you have any balance remaining after the 15 months are up, you will be charged interest on the remaining amount at the standard rate.