My opinion of cost effective is $50-100 on nutes is a cost effective investment per potential pound of harvest give or take if you found something that works for you. There are people who don't buy the expensive ones and do well, but they are probably way more educated in the ways of fertilizers than I. If you really knew what was in it, and what exactly your plant needs/wants, I'm sure Miracle Grow could be put to quite good use. I just would assume you would not be maximizing your potential if you used only MG all the way through from seed to harvest. The overpriced Hydro nutes have specific schedules and proportions for each stage of plant development.
I personally use GH 3 part flora, as well as most of their suppliments. I think they are retardedly overpriced, but they produce great results. Definitely reccomend GH nutes. For cost effectiveness, look into their 2 part, or their dry concentrate. For suppliments, figure out what is in the GH suppliments, and buy cheap alternatives. I would however stick to a quality base like the 3 part, or 2 part.