Completely disagree with it being in the BM shop, it's an untradeable that isn't a weapon/armour. Should be in the U. Points shop, if you're going to have it like OSRS where you lose it on death no matter where you are in the wild, then the points should be 2-3k max. If it's kept on death then my suggestion would be have the price at the highest in the shop at around 7.5k points, this way pures actually have to play the game to get it. If I'm honest it should be lost on death to make it more of a risk since it gives a decent advantage in the wilderness.
@Palidino