@Zerik I really jumped in last year with these exact same questions. This is where I’m at today...affordable products in my neighborhood..
Lowe’s
Bag of red lava rock, ~$3
-It’s usually wet because the bags sit outside. I let it sit in the sun until thouroughly dry, or pour it into two big flat pans and bake in oven on 500* until obviously dry.
Dump into tub or bucket and smash down with sledgehammer till I’m tired of hammering, sift fines repeat..I can process a bag in about an hour after dried. Work right!!?..$3.00
Lowes
56L bag of soil conditioner ( it’s pine bark )
Sift fines
Lowes
Bag of pea gravel, ~$3.
This is not ideal. It’s a good size, works as a very large grain sand, allows drainage, but has no porosity cation exchange etc..
Lowes
Bag of perlite, $more than 3, ouch (optional, arguably not a must or even necessarily an ideal component..wish we had cheap pumice in TN)
Sift fines
NAPA
Floor-Dry #8822, ~$4
Sift fines. Do not breath this (dust)..at all, use the wind. Dust is essentially glass powder and you will die, right there, first bag.
I believe these components are enough to make a good mix. Omit perlite perhaps and get a huge tub at Lowe’s for $10..you just spent $25, and can mix a bunch of soil.
The ratio of mix, I can’t tell you what’s best. How often do you want to water? I aim for 2/3 inorganic at least.
As for digging up trees, I say go for it. Expect to kill. I’ve been digging what many call ‘trash trees’ in ditches and places where they are not wanted anyway, and have learned so much over the past year from mistakes. If I hadn’t jumped in, I wouldn’t have learned. The YouTube channel, Appalachian Bonsai, is super for harvesting techniques. I’ve learned that if I’m going to dig up a tree, I’m going to treat that tree like I’m picking up a sleeping newborn from a crib. Don’t cut corners. Sometimes it’s better to put the dirt back and leave the tree be.