I just picked up a pair of l.e.d. flashlights from Costco for $14.99(originally $19.99). They're crazy bright and have three modes to use(50% power, 100% power, and SOS/strobe mode).

Pkg. says it's 160 lumens, lights up to about 100m, and should last up to four hours off of three AAA batteries. All I need to do is get a pair of flashlight holders to mount to my handle bar and I'm set.