Depends on the set-up. Outdoor soil costs nothing more than the seeds. Indoors the biggest cost is the lights, which can range from $100 to $500, depending on set-ups. Hydro a little more with the meters adding on another $150 and ferts/etc another $75. IMHO, a DWC hydro set-up will cost you around $350 without utilities to get going. It will definately pay for itself with the first plant.