Read Rhizome's guide to growroom setup.
And remember that initial investment vs. long-term investment is a factor. A basic hydro system is just a tray, a medium, and a res with a pump in it. I think I spent less than $250 on each of my flood/drain table systems. If you are handy, your costs are lower.
Soil is a cheap initial startup, but pots and dirt DO add up and dirt is not re-useable.

Use one room for veg and one for bloom, and read the first link in my siggy for some basics.