I may be a little late for this but I built a LED set up for a nano salt water tank I had. I purchased everything except the wire and soldering iron from
http://www.rapidled.com/ for around $60 (6 leds, heatsink, driver, etc). They also have no soldering options too. I did extensive research on on the topic at nano-reef.com which has 100's of led builds but were for salt water coral which have different requirements as far as aesthetics, grow requirements, and color temp go. You could
easily build a LED set up like you are discussing. I have pictures of the light I built if you would like me to share them. I would think you would use mostly cool white leds because they are in the 6500k range. I personally don't know how important the other colors are that you have listed. In salt water the other colors were added for visual effects and not a requirement for growth. I live in NC so I do not use an indoor light for CPs so my only experience is with saltwater as far as lights go. Maybe my experience can help you out with this LED build though.
This is my first post
been lurking for a long time...lost of good info in this forum.