A lot depends on what you're starting with, and exactly how and where you want to grow. Inside? In a cabinet, closet or dedicated room? Outside?

When I first sat down and decided I wanted to grow my own, I was starting, literally, with nothing at all, because my home had burned down. I had no tools or spare PVC, or duct tape or staples or mylar or pots or anything. Starting from absolutely nothing at all, and buying quality stuff (digital ballast, a real cooltube, good centrifugal fan, good carbon filter), plus tools, plus cabinets and mylar and caulk and a caulk gun and white paint and brushes and primer, yada yada yada yada...I *thought* I could do it initally for around $800, but it turned into probably $2500ish before all was said and done, maybe three grand.

I know, that seems crazy, but all those little things add up, and there are so many! Canning jars, yarn and hooks for hanging, water catchers for under the pots, seeds, soil, nutes, mylar, staples, a drill and bit set, a holesaw kit, CFLs for vegging, reflectors, timers, extension cords, Great Stuff (the cans of hardening goo stuff), weather stripping, rubbing alcohol, duct tape, electrical tape, chains and hooks and nails and screws, a hammer, some screwdrivers, growing book or two, ph kit, jewelers' loupe, darkroom louvres, a bit of lumber, three cabinets (mother, veg, flower), oscillating fans, little AC fans for the veg boxes, a variety of pots, scissors, snippers, razor blades, cloning gel, a little 30-site EZ Cloner, spare HPS bulb, vermiculite, perlite...and I probably forgot tons of stuff I ended up needing. It just went on and on, and my setup is by NO MEANS large at all -- it's actually probably on the small side.

Basically, what I'm trying to say is, estimate how much you THINK it will cost and then double that, so you don't end up getting halfway done and then dragged down by not being able to afford all the little things that you didn't even think about at first.