I'm with Chris, seems rather expensive.
Has made me think, do any of you that make these smelly nettle/comfry teas, have you tried giving it a good regular stir.
I am thinking that the bugs that produce obnoxious gases generally thrive in low oxygen environments, so if you give it a good stir to get oxygen in, maybe it will be ready sooner and without such a bad smell.
It's just a thought, but maybe somebody could try it.