I have to take my pictures while the rest of my family is asleep, so it's usually pretty dark out.
The trick is to use full spectrum light bulbs. I special ordered my bulbs so I could get 25W CFLs that are BRIGHT, but wouldn't create as much heat as non-CFLs (so I wouldn't burn the dang house down if I flipped on six at once).
Everything else about my setup is cheap... cheap camera, PVC-pipe frame for my light box, posterboard background, clip-on aluminum light fixtures from the hardware store. But the light bulbs were key.