Soil and Nutrient Q's

I am contemplating starting a somewhat large garden in a new room. I am use to using Fox Farms Ocean Forest on my plants and am pleased with the results thus far,the problem is that i am starting many more plants then i am acclimated to and do not think buying hundreds of gallons of fox farms is very cost efficient,how do i attain alot of soil cheaply?. which leads to my next problem which is also due to the large number of plants i am thinking of having which is how do i make such large batches of nutrient to feed a larger number of plants,whats the best thing to buy to prepare the nutrient solution in to keep water temps and such at the correct levels? whats the best way to place many plants on a flat floor so that it is not impossible to reach the plants in the center to water them?

I can feel you here. I like soil for ease but at a point it gets to be too much of a hassle. You can see why croppers all go hydro. I am switching to cir because its so cheap and effective. I like it a lot so far cause I like to hand water and be connected somehow. Coir has way different moisture retention than soil but very similar in use.
Either way I have a great compost pile from spent soil and coir.