I know this is going off topic slightly, but we are all still thinking about nick and his shell dweller tank!!!!
Alright this is what I would do!
If you are not looking for plant growth I would use a set of white cold-cathode tubes. You can get them on ebay for next-to-nothing. (Word of warning though I bought cathode bulbs off ebay before and both where broken when they arrived). So you might want to pick them up in your local computer store.
The wires on the cathode kit should be long enough as is, if it ain't you might have to do a little wiring but its no biggie!! First glue the two tubes to the under side of the lid (the bulbs are in sealed water proof tubes so moisture should not be a problem and therefore you will not need a condensation lid. Then drill a single hole in the lid towards the back and thread the two wires from the cathode tubes through. Then its just a simple matter of plugging the wires into the supplied transformer and hooking it up to an AC adapter.
If you do your homework you should be able to make the lights for under 10 squids.
white cathode light £7.45
UNIVERSAL AC/DC 3-12V POWER ADAPTER.300MA £1.99
Not bad eh!!
A couple of pictures you have most likely seen already!
The cathode kit
The ac/dc adapter
The white bulbs installed on my fry tank.
The two bulbs kick off a great amount of light
Hope this is some help nick, let me know if you have any more questions.