I have a local ag store that has a gardening section. I just ask them what they can order, and I get great deals on big bags of stuff like perlite. I got a 50lb bag of kelp meal for the same price as a 10 lb bag on Amazon. Free shipping if you can wait until the weekly truck comes in. Give your local businesses a chance.
OP, if you are loosening soil that isn't in a container, I don't know if perlite is the answer. I would think it would get ground into dust or blow away if it wasn't in a confined area.
