The kit comes with a six foot micro USB cable and the pad w/o the fan comes with a three foot cable as well.
I would get the kit but it also depends on where you want to use the pad (the pad with the fan will make noise and isn’t optimal for the night stand but is still quite enough to keep in the bedroom as long as it’s on the other side of the room) and if you plan on owning any other devices that are wireless charger compatible that will be able to take advantage of the 7.5watt(iPhones) or 10watt(Android) I’m assuming the headphones can’t charge wirelessly above 5 Watts.
So if the only thing you plan to use the pad with is the headphones I recommend getting a 5watt pad and cable of your liking with an old charger (5 watt pad do not need quick charge power bricks) to save a considerable amount of money.
On the other hand if you plan on getting more wireless devises and want to future proof yourself get a more powerful wireless charger 7.5/10 Anker also just released their 15 watt pad which a handful of current devices can take advantage of but currently preforms nearly identically to the 10watt pad but will charge upcoming phones with wireless receivers better suited to receive 15watts significantly faster.