Triblade

So, I got an Unusual War paint called Organ-ically Hellraised from a Scream fortress XII crate today and MAYBE no one has ever got it before (cause i tried to search it but there's no result) . Its a Mercenary grade and a Field Tested Warpaint. Also, the Unusual Effect is Hot so, i thought to put it on the Flame Thrower. The question is how much should i put the price for this skin?? Like how many keys would it be? Thats All.