If money is a problem here's what you do, get a plastic bucket and fill the bottom with shredded paper (anything, tissues, junk mail, etc). Go dig up some worms and put them in there, as many as you can find. Red wigglers are best but any soil worm will work. Save food scraps that are not meat or dairy. Throw some into your bucket, cover with shredded paper, and only add more food when the other food is mostly gone.
Keep doing that until your next time to plant. Mix this with your soil and plant, and keep making worm compost. Every few weeks throw a quarter inch of worm castings on the top as mulch. Don't use any nutrients. You don't need any anymore. The worms will also bring beneficial bacteria and fungi in their bellies to fight off bad bacteria and fungi, you'll get some awesome predator mites to fight off pests, and the compost provides all the nutrients you need.
You know what has nitrogen? Old composted plants. Phosphorus, potassium, magnesium? Composted plants. Selenium, calcium, every other nutrient that your plants need? Composted plants. Amino acids, enzymes? You guessed it, turns out composted plants have all the exact same things plants need. It's the cycle of life, how nature does it Just water with plain old water, filtered is good, no pH balance necessary. When you make it yourself, it's the cheapest nutrient around, all it costs is a bucket, and keeps your food scraps out of the landfill and your nutrient runoff out of the sewer system.
