I have seen a few brands that do have advertise as having the ingredients of the SFG mix but you can also make your own. If you go that route, you can get the ingredients from practically any garden supply or nursery store.

Not sure what area you are actually in. But in Fredericksburg there is one Home Depot that ordered some. A local new non profit started up here and is using the SFG method and HD gave her some deals to create raised garden bed kits to sell to people at a discounted rate. So HD ordered extra for their store. its the store on route 3. Here is the info. Im picking up a few more trying to convert my existing beds slowly as I can afford it.

1201 Gateway Blvd, Fredericksburg, VA 22401 : (540)368-0515