I recently built my own light strip for a 55 gal aquarium and I
thought I'd share my plans. I had two goals: lots of light, little
money. Time to completion was about three hours. The materials have
extra left over: the gutter only comes in 10' lenghts, so it is enough
to make two strip lights, and I only used 1' of aluminum flashing, so
I have 9 additional feet left over. The materials can be found at any
hardware stores, but I found the lowest price on screw-in compact
fluorescent lamps at Sam Walton's store.

Materials:
10' vinyl gutter (white) $6
Two gutter end caps 4
10' extension cord 3
3xdouble light socket (screw-base) 9
Spray paint, textured black 5
Aluminum flashing, 12"x10' 7
6x20W, 65k screw-in flourescents 30
Misc screws, pop-rivets 5
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$69

Tools:
Wire cutters/strippers
Pliers
Hand saw
Drill
Sand paper (optional)
Screw driver
Pop-rivet tool (optional)

A few construction tips:
- I used pop-rivets to fix the end caps in the gutter, but #6x3/8"
screws would work fine.
- Disassemble the light sockets and replace the screws holding the
socket together with #6x 1 3/4" machine screws.
- Make reflectors out of 4"x12" pieces of aluminum flashing. I tried
without reflectors, but the gutter got fairly hot. Use a couple of
nuts on the machine screws as spacers between the reflectors and the
gutter.
- I used fairly 'fancy' black spray paint that has sand to give it a
textured finish. To give the paint a better surface to adhere to, I
lightly sanded the gutter surface.
- The gutter was still warm to the touch, so I drilled ventilation
holes through the vinyl, but over the reflectors so that light doesn't
leak out. With only these holes, my tank stays at 80-82 F when the
room is 76 F, so fan cooling is unnecessary.