Normally I would say a bundle.
but. With the other pricing in this game, and the previous editions.
I'm rather certain its individual arrow.
BUT! in the current playtest, I don't think ammo is destroyed when used.
...though I think arrows may have a stipulation that they lose their magic when shot... I'm not sure what Viper arrow does in general. Not sure if its magic or not. so you'll have to check for that kind of interaction.
