I am going through the same thought process. I found the Electronics, Lighting & Gadgets forum and this thread in particular got me thinking. I have to outfit both my wife's bike and mine with lights, so I think I'm going with the 26650 flashlight route. I'll order one first to see if it's enough, then decide how to proceed from there. The outputs are amazing for a $25 ebay light. Others will chime in on how it's not the best way, but I can outfit both bikes, with two lights each (if necessary) for a total of $100.

Check out SoCalRider's video here.