I am only growing one plant for now but plan to maybe grow more in the future if this one is a success. There are no hydro stores near by so I'd have to get my nuits from Walmart or Lowes or a local hardware store. I am looking for a method that is fairly simple and budget friendly. Will I still need to add worm castings after I add the liquid nutrients or will the nuits be enough?
If you want to keep it cheap and easy, look for a bottle of liquid plant nutrients/fertilizer. A small bottle will run you around $10.00 at any local big box store that has a decent gardening section. Whatever feeding instruction it has on the box, start with 1/4 of that for smaller plants, and work your way up to the full instructed amount (e.g. suggested 10 drops per 1 litre of water would be 2 or 3 drops per litre of water). Anything that has an N-P-K ratio with high levels of nitrogen and lower levels of the P and K is what you want. A good vegging nutrient would have an N-P-K ratio of 10-5-5, or similar ratios. The N-P-K ratio represents the amount of Nitrogen (N), Phosphorus (P), and Potassium (K) available in the nutrients. For the first part of your plants life cycle, it will want more N, then in the flowering cycle, it will want more P. So two different nutrients will be needed throughout the grow.
EDIT: Avoid Miracle Gro, or any slow release mineral crystal based fertilizers. Liquid, water soluble nutrients are the way to go. Also, make sure to water without nutrients between feedings (watering with nutrients).
The worm castings may help during flowering, but it's not necessary. There are many different ways to grow!
Check out this very simple DIY setup that was originally designed to run 6 lights, and now runs 12.