I never really think of using Verizon as an option to purchase accessories such as headphones as there are far better
financial options available. If you use Bill to Account with Verizon, the total amount of your purchase is due on the next bill.
I usually buy stuff in pairs for the Wife and I, so I typically end up spending a few hundred here and there with Amazon or Apple directly. With either my Apple (Barclay Credit card) or Amazon, I can get 6 months no financing charge on most purchases.
I see T-mobile lets you get accessories and pay for them over 24 months - no interest.