Different target groups of consumers. Besides its just a hobby. Those who cannot afford or who like experimenting can still get good results if they get good advise from sifus like Diana Walstad, Dom,etc. DIY stuff can also be instant if you know how. But slightly more work.

Those who like to get good results from reliable ready made methods can also do so.I suppose you will also need to do some research before getting costly stuff. Conditions may differ form country to country, e.g. water quality, temperature, lighting,etc.