I've checked out a couple of "super soil" mixes and over $40-60 for 27 L seems insane so I skipped out on them.stright away.
I also find the mixing, composting and cooking strangely therapeutic so it kills two birds with one stone.
If you want pests, diseases and wood chips in your soil mix go to Bunnings.
If you want someone to capitalize of your laziness go pay for overpriced premade soil mixes.
If you want to have healthy plants that only need water feedings till harvest go make a hot compost/super soil mix, tend to it once or twice a week and 8-10 weeks later it will be ready for potting.
Get a worm compost, all your kitchen scraps go in and you get quality worm castings (poo) in return while your worms will breed and multiply. I personally started with a small worm compost of red composters and over the months collected regular worms in my garden (known for breaking down other organic material such as leaves and branches that red composters ignore), few years later my backyard has worms everywhere, under pot plants, in garden beds, soil mixes etc. and I have half a dozen worm bins on the go continuing to be topped up with organic material. In the span of 3 years my worm farm has probably expanded by 20x with little maintenance.
Getting some chickens pays for itself too as they're walking fertiliser machines for your yard, give you eggs, hunt pests and overall lovely company. Your general chicken feed mix from stores is rich in nutrients and ends up in the chooks droppings, for example the grains are rich in phosphorus and potassium (n-p-k) and most of it goes into the poop. The poop needs to be aged/composted/diluted etc. Egg shells are also a source of calcium to be added into your soil mix.
If you have access to worm/chicken castings you can make compost teas to keep/feed your organic soil full of microbes, beneficial bacteria, fungus and so on.
what about if you 2 guys wanted to make your own soil available to the public ,
how much worm castings / compost would you need to make ? ,
how much land /factory space would be required to produce a large amount of it ?
how much would the ingredients cost to feed / make castings or compost ?
what amendments would you add & how much do they cost ? ,
how many employees do you need to make the mix if making by hand ?
if you use a mixing machine how much is the machine ?
how much is lab testing ?
how long will product testing take ?
how many bags used for testing at no return ?
will you need to borrow money , how much are loan repayments ?
employees , super . work cover , wages , vehicles ?
the list can go on & on ,
so how much do you reckon you'll charge for your 25 liter bag of potting soil ?