SPM and Aeration: Garden stores have promix, which I have switched to because of the ease. I buy lava rock in a bag from the landscaping yard down the road. I use a sledge to break the large chunks up, in an old animal feed sack in the driveway. (watch for added salt nutrients in perlite)
I also like adding a little Pine Bark Fines to the mix, I buy this for $4 a bag at Home Depot.
EWC: I make my own EWC but have also purchased some from someone I found on FB marketplace. I have horses and also make tons (literally) of compost yearly. But with a bucket and some searching on FB or Craigslist you can find free manure. Give horse manure at least 6 months of “cooking” before using because of worming medication. Once I see worms in it, I know it is ready.
Amendments: Luckily, I live near an organic supplier. Also, I grow a lot of cut flowers and have a greenhouse, so I purchase in bulk. I would recommend buying online from the closest organic grower supply. Search online because there are a lot of great organic suppliers that are local. You can pick up.
BIOCHAR: I buy hardwood charcoal and break it up. I know it is kind of ghetto but it has worked for years. Something like Cowboy Brand Lump Charcoal.
I buy 50 lb bags of kelp from this website.
This is what happens when Tommy logs in to OG REALLY high!