I heard that it's not worth wasting good bonsai mixture when it's for growing
Well if you live in a part where there is a lot of rain, you might want to get some more free draining soil. Otherwise roots will only grow at the edge of the pot. As the inner part stays to wet, and has almost no air.
Did you Google Nigel Saunders on Youtube? Like i told you about two weeks ago?
He lives in Canada, and you can learn some basic cheap soil mixtures that work very well in canada.
He has a few 3or 4 i think where he does some collecting in the forest. And every few years you see the progress of that.
All others tree's he started in his garden, got as gift, bought as young plant, or started from seed.
So i call that actually all raw material. So basic's you can learn from him.
For the refinement and wireing you need to look at other more professional bonsai guys. As he does only clip and grow Technic. But that is ok for the first years of the growing stage.