If you want money saving, then get a good substrate... but I'll be the 1st to tell ya... there ain't too many plants that do ok without at least some fertilization.
Moss balls and java moss are some that do incredible with low light, dont care about substrate, and need no fertilizer. These also do great with the "catfish, characins, cichlids, livebearers, rainbowfish, crabs, shrimp, snail" you have listed. Best part about these mosses, super cheap and you only need 1 moss ball and it will spawn many others, and your little clump of java moss will quickly become many large clumps of moss and grow on everything. Shrimp LOVE moss balls. Java moss grows into any wood you attach it to. Its almost impossible to kill these plants as well. Also, nearly any fish store will carry these... So if your just starting with plants, then you now have your starter plant selection.