you can get them that work from like a bbq gas bottle too but i didnt see them for years now , seems the really cheap ones look not too bad and you can get the gas cans at big w and the like 6 for $10 still in some places .
what sort of a boss though , rover ? . different ways of removing them sometimes , some hard most easy .

and dont get heat close to the seal , nice wet rags n stuff around it