I am going to throw the money for the Lumotec IQ Fly light and the Dymotec 6 bottle dynamo from Peter White.

If I had put a little more thought into my build, I would have gotten a hub dynamo. Now I am in a position where a hub dynamo is not an option, unless someone knows where I can get a rear hub dynamo that will take a 8 speed cassette. (I have a front hub e assist motor)

I was considering the Magten lightset (I may still get one just to play with), However, I am not confident that it will work with my particular build. Also, the IQ Fly is supposed to put out 40 lux and I have seen the beam pattern on Peter White's site. The Magten light is only rated for 15 lux, and I have no idea what the beam pattern is like.

The Magten is cheaper, might be doable for a child's bike. The Magten is a always on light, kind of like a daytime running light. They are also supposed to meet the German standards.