I love these roll-your-own lights and DIY mods. Wish I had the drive to make one. But I'm lazy. I know my limitations. My version of DIY usuallys involves zip-ties or black electrical tape.

So last autumn I bought a nightrider nr-20 digital on eBay for $65. The remote-on switch was malfunctioning and even though it was perfectly usable with the built-in on/off switch -- I sent it back to nightrider and they fixed it. They charged me the standard $20 lifetime service fee.

This light is so bright it puts everything that's not HID to shame. I can light up the road 100 feet ahead of me, and have mistaken other cyclists reflectors for bike lights due to the brightness of my nr20. It came with a battery pack and digital charger as well as a helmet mount. Sometimes I'll even use it on overcast days - it helps ensure I'm being seen by motorists.

Good luck! Bike lights rule.

PS. I also have a bunch of LED lights, including one that uses a 3 watt luxeon emitter. IMHO the LED lights don't cast as anywhere near as broad or bright a beam as the nr20.