Originally Posted by agarose2000

Best options for bang for buck and convenience:

BEST FUNCTION & PRICE: 2 x AA option: FENIX L2D.
$55ish. It's worth it. Light, small, and has useful settings including a seizure-inducing strobe. 180 lumens, easily for 75-90 mins depending on your batteries. I don't think this can be beat for performance/weight. I've actually made this my primary running (not cycling) light with a headstrap. Fenix also has awesome customer service - you absolutely won't have any problems with this light. Nothing with similar features & build can compare for price and performance.

LOWEST FUNCTION & PRICE: 2 x AA option: Terralux Lightstar 220, with Romisen coming in a close 2nd
The Terralux is $28 from a US vendor, and is every bit as bright and effective as the Fenix. The Romisen is also as bright, but not as hefty, whereas the Terralux feels bulletproof. A tad bigger and heavier than the Fenix, and no strobe function. This has been my primary light for bike commuting - one on the bars, and if I feel like really luxurious lighting, I'll go one on the helmet as well. Same runtime as the Fenix.