I am all for DIY (I DIY'ed my entire setup except for my current LED
lights), but almost every DIY LED
lighting system I saw looks like a frankenstein project with wires and drivers hanging out all over the place. If you don't mind that type of look, go for it.
If you want a more "finished" look, I highly recommend buying an LED
system, but you will be hard pressed to find anything for less than $300 for a 4' tank.
These are very popular, but use only blue and white LED
's. I use similar lights over my 125 and can grow and keep anything. 2 units will run you right around $300.
2 Dimmable 120W Marine Organism Aquarium Coral Reef Fish Tank LED Lamp White US | eBay
The next step up is a more full spectrum LED
setup. These look real nice and they are what I would get now and would have bought when I got my LED
's...but they were not available back then. They will run you a little over $400 for 2 units.
120W LED Full Spectrum Coral Reef Light 55 x 3W Bridgelux LED Brand New | eBay