Be very weary of web sites that are selling spore syringes... I had to fight with SporeBank to get my order. They completely ignored me for over a week! I know they have affiliates that they partner with like University Scientific Corporation, so you might watch where you order from.
Everything I've read from the Shroomery says that you should be pretty safe with the vendors that they list on their forums.
Tahoe is correct on the grow medium, but please do some reading before you begin. Sterilization and contamination are very large factors when creating your little shroomangies. If you contaminate them, then you're potentially eating something unsafe, and harmful.