For those who can't find perlite without fertilizer a recent trip to two local Home Depots in the LA area showed shelves full of two cubic foot bags of perlite without fertilizer. These are about the size of a sofa seat cushion so be prepared for a lot of perlite if you have a small collection of plants. About $17US.
And for those small collection growers in California OSH (Orchard Supply Hardware) is carrying the Black Gold line of soil amendments including Sphagnum peat moss in two or three different size bags - again without fertilizer. There is also a SuperMoss brand of compressed long fiber sphagnum moss again in two or three sizes. The quality is better than the Mosser-Lee stuff which many of you sneer at but either is better than not having a safe substrate to plant in. OSH sells perlite without fertilizer. Just get a ticket (if in stock) and take it to the register. They'll load it in your car.
As always wear a respirator or a dust mask when working with dry perlite.