"The question: Are there lights for bikes using that same technology but could be cheaper and even work as well as those expensive and heavy rechargable sytems? -- the ones with the dual headlamps and batteries that go in your bottle cage "

You asked...........The answer in NO........not even close. The expensive and heavy lights are worth more. You get what you pay for. The lupine LED lights are probably the brightest around ,but will not "hold a candle" (sorry) to the more powerfull halogens and the HID's. I have a nightrider "Blowtorch". I have an "Edison 10" from Lupine on order, I need more burn time.