Welcome to the madhouse Stephen
I think there are many ways of getting good results in a garden. Some are faster, some more expensive, some less friendly to Nature, and on and on.
Around here there is a very strong tendency toward tryng to work as much as possible with materials that are on the site and as little as possible with materials that have loads of embodied energy.
Vermiculite and peat are both pretty high in embodied energy and neither is really renewable in a present tense sense of the word (peat is organic material and renewable, but like mature forests, it takes a long time in human terms).
You can accomplish amazing things with home made compost. Leaf mold, also home made and if you have deciduous trees incredibly easy to produce, does wonders. Vermicompost can do great things for your plants.
All of these do one thing that is more important than anything else - they bring microbial life into your soil, establishing the soil food web that is the fundamental basis for growing healthy plants.