Just dig up some soil and seterilize it, then add some sterilized perlite, a 4 pound bag cuost me a whopping 2.50 at walmart, and 4 pounds of perlite is a shitload, you could just use perlite as your medium, some greenhouses use it, just wash it first to remove dust and ph it to 5.5, then have your way with it

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"If its good enough for God herself to put on Mother Earth, then its good enough for me." You've got a gun, I've got a plant, who's the real criminal?