The highest quality DIY stuff would probably be ReefLEDLights, but that quality also comes at a price. Bill, the owner is a sponsor here. They sell binned high quality CREE diodes. RapidLED also sells CREE and has a premium line but I don't know if their chip selection is as controlled as ReefLEDLights. That being said, I did just put together a DIY with diodes from Rapid and love the way it looks compared to any of my "Chinese no-name chip" Par38/30 bulbs.