@tomc Hey Tom, would this be something worth considering?
https://www.amazon.com/Bonsai-Tree-Soil- ... +tree+soil
I hope that link works. It's two quarts of Bonsai tree soil that says it's supposed to have the minerals and nutrients that they say "any" Bonsai tree needs. It's fairly inexpensive so it seems like a good deal as long as it really is good Bonsai soil.
I got the liquid and pellet type fertilizer through Amazon and that stuff seems okay. I guess Amazon has a bit of everything.