<I use a few 6700k compact fluorescent screw in bulbs and clamp on shop lights. I put 81 watts on my 29 for under $30. >
that's what i was about to recommend. go to HD and get a 12' cord, some incandesent sockets, a time, some compact fluroesent "daylight" bulbs, some pine wood, a can of black spray paint(cheap stuff, high gloss) a can of white primer paint, some nails and screws and a sheet of 200grit sand paper. build yourself a canopy to fit over the tank out of the pine, put down 2 or 3 coats of primer, sand the primer smooth, spray on a coat or two of black paint, wire the sockets together and screw them to the inside of the canopy at even distances(leave the inside of the canopy white for better light reflection) then screw in the bulbs, set your timer and enjoy the plants.
or you can get a 24" shoplight and 2 daylight t8 bulbs.