It depend on how big you are trying to go.

A half dozen plants in a tent: You could veg in the closet and use a second tent for odor control (carbon scrubber or ozone). With a 600w bulb in the tent (on 12/12) and a bunch of cfl's in the closet . . . your power bill will jump about $40 a month and you'll knock out about 8oz every 8 weeks.

Going big with 60 plants in one bedroom . . . save all your money for a good lawyer.