Potting mixes out of only local materials?

I'm working on developing a small permaculture nursery, and I'm hoping to develop a potting mix based on local or waste materials. I don't mind buying in fertilizer ingredients for the mix, but I'd like the bulk of it to be locally sourced. The hardest component to replace is the perlite: has anybody found a good substitute? The mixes have to be as good as or better then commercial mixes. I will be running tests under grow lights this winter so that I have a good mix all lined up in the spring, and I'd like some input.

Partially decomposed wood chips. Just to that point where it starts to get spongy. They'd be light weight, absorb and slowly release water (see hugelculture) and add good texture to the mix to increase air pockets for the roots to breathe.

These days I always put a few inches of wood chips into the bottom of all potted plants.  Since I started doing this, I have actually started keeping a few alive.  If you start with aged wood chips you reduce the amount of nitrogen that is tied up when you mix the ingredients. With fresher chips you may find supplemental nitrogen necessary for best plant growth.

If you do look into do doing this, look up information on ramial wood chips which is the kind most landscapers produce as a waste product.