Check out growmau5 on YouTube.
He gets huge yields with his diy LEDs.
If if I had the money, I'd buy one of his cutter kits and make a light. But until then I can dream...
The technology is developing so quickly... The new Cree's are coming out soon I think. Seems like every 3 months there's a new bigger/better diode or driver or whatever.
Once the price drops I'm on it like white on rice. By next year this time, i hope to have an led running in my garden.