I only kill snakes if they're poisonous and in a place I'll be back to in the dark, or close to my house.
Personally, I will never kill snakes to back bows, and I don't think buying skins is a good idea, because it promotes killing of snakes for profit. If you want to kill your own and use the skins, that's fine in my book, but I object to the wholesale killing of snakes for the sale of the skins. I think it should be illegal, like the selling of other wildlife parts. Just my opinion.