To the best of my knowledge, General Hydroponics MaxiGrow & MaxiBloom are the most simplex "Lucas formula" and are the cheapest GH products.
MaxiGrow & MaxiBloom are powders that you mix with water. Use a glass jar with hot water, add powder and shake for 5 minutes until there is no sediment on the bottom. I use a milk frother which really works well to mix the powder
I use 7 grams of GH per 4 litres (plus 5ml of Cal-mag)... & pH to 5.8