LEDs are still pretty impractical... you can build your own LED array cheaply, but it would require MANY hours with a glue gun/ soldering iron

you can buy ledgrowlights, but they are still too expensive to be worth it

IMO, stick with HID lighting or spectrally corrected flouro lights... look at the spectral distribution graphs on the different bulbs available at your local pet shop.. you will be impressed

right now i am using one standard warm white cfl, 2 hagen aqua glo tubes, one zoomed ocean sun tube, and one exo-terra 8% UV-B tube