You can mix your soil yourself. The soil mix I use is amazing, and you just add water, no fertilizers, as the soil already has 60-80 pounds of amendments.
1/3 compost...if you can add work castings/vermocompost to it, even better, but no more than 1/3 worm castings.
1/3 peat moss
1/3 pumice or perlite.
That is the basic soil mix. To this mix, add, per cubic feet,
Alfalfa 1/2c
Fish bone meal 1/2 c
Neem meal, 1c
Kelp meal, 1c
Crab meal, 1c
Oyster shell flour, 1c
Gypsum, 1c
Rock dust, glacial rock dust, basalt dust, azomite, etc, 3 c
If you have it, innocuoate with lactobacillus bacteria.(Google "making lactic acid bacteria serum)
Miz it up, get it wet, put a tarp on it and wait ,4 weeks, and you have super amazing super-soil .