the raw materials are very cheap (like $1 per kg, agricultural grade) and the end product sells like $10 per liter (by weight, ~100 gr raw material, the rest water)
so the multiplier (price/cost) is like 100, pretty common for chemical products
the whole hobby-industry is like this: promote nutritionless sand as substrate to replace soil use the expensive fert (surprise! they sell it too!) to enhance plant growth use expensive 'full-spectrum' light use heater to give vertical water movement co2 tanks (you can make DIY using sucrose and yeast)
and of course without saying, spreading FUD to fuel collaborative manipulation
in the end, i end up just using soil, sun, no fert, no tech ... plants had lived for centuries on those with great success!
hey ... maybe i should go sell some ferts :D ... i still have bags of KNO3, H2PO4, MgSO4, FeSO4, ZnSO4, MnSO4, Na4EDTA lying around collecting dusts