I don't buy any i make my own compost and i have animals, but if i ever wanted animal manure i always had to buy it in the us , hell guano is like $60 for a container
i buy microbes tho
.
this is the only way to do it. being sustainable is the way to be.
and i buy microbes as well as other beneficial fungi.
since ive been living in the woods i havent bought any though, found that the forest floor is littered with benifcial microbes and fungi. i just go out lift some leaves and theri is just massive colonies of fungi. so i take a bucket of it and add it to the soil. the colonies have already started to grow again in the soil i have