Im new to this, but the way I understand it is that your nutrience dont have to be perfect, however what is important is that you have the correct PPM depending on the age of the plant.
Picture Page 36
Ron mentions here, among other pages, a mixture of:
1 teaspoon - miracle grow for tomatoes
1/4 teaspoon of Calcium Nitrate
1/4 teaspoon of Magnesium Sulfate
Per gallon of water
This should be a much more affordable blend vs the "secret sauce" from retailers. If you could find cheap, generic miracle grow, you would have a very cheap fertilizer.