I caught the end of a program on tv the other day that showed a couple who had a greenhouse and said because they didn't use potting soil that they could use their space more efficiently and have more abundant crops.
Go to a builders merchant for vermiculite. In the UK Keyline and Jewson both supply big bags for about ten pounds. Otherwise they will sell it at any garden center, along with cow poo, although they will charge over the odds for the vermiculite.
If you go to your local nursery you can buy both vermiculite and cow poop. Please be careful with these where magic mushrooms can be cool they can also be very dangerous and lead to death.
Do not consume mushrooms unless they are correctly identified by a professional! you need to look online for the Bell jar method of growing mushies. Vermiculite can be found anywhere plants are sold, like Wal-Mart.
