Those CFLs laying around can be utilized for seed sprouting/seedling stages.
Nothing wrong with a good ol 400 MH/HPS combo ballast. That's gonna get ya into a 3x3(ish) area, for 3 plants, plenty of space IMO.
Premade tents, even the cheaper ones will get the job done. The DIY box route can add up to the same cost in a hurry. Also with tents, the reflective surface is already taken care of, ventilation ports are there, and they're generally pretty light tight. Some have pinhole leaks, and zipper issues, all easy fixes for little or no cost.
I like 2 or 3 gallon cloth pots/felt pots/ whatever brand I can get for the cheapest. I like the way they drain evenly, and air prune the roots. Look up air pruning if you don't know what that is.
Research the ventilation issue, search the forums for direction on odor control, and air movement. Small tent= small fans/filters= cheap enough.
You'll definitely want (need) a PH meter, and a TDS meter. They don't have to be expensive either. The cheap ones work enough, they may not last forever, and need regular calibration, but you gotta have something. Get a bottle of calibration solution for the ph meter as well.
These forums will be a great resource for information about grow mediums and nutrients. Convince yourself, and accept the fact that less is more, because it is, certainly in the beginning days.
Growing can be super simple, or super complicated, and there are loads of conflicting opinions on every subject involved.
Meet the basic needs of the plants, and you will be rewarded.
