i just bought a 48" 120 blue led strip off ebay for like 6 bucks with shipping sent from china. it only took 2 weeks to get them. they are intended for automotive use so you do need a 12v converter, unfortunately this cost as much as the leds. just kinda held it over the tank with the other lghts off to see until i attatch it, and all i could say is WOW! really makes things pop. definatly worth the 15 bucks total.
i also bought a white set, and when combined puts off a nice color of dim light. i'll probably add timers to the new additions and go something like this...
moonlghts
blue led strip 30min
white led strip 30 min later
actinics 30 min after that
daylight 1 hour after that
...and opposite at night.
should be a nice suttle wakeup and bedtime transition for all the critters.