You'll be lucky to get 300 lumens from a 3AA light. I purchased a couple of Chinese flashlights last year that claimed 1200 lumens - they are well drowned-out by my 600 lumen Niterider rechargeable. It's not even close. And the beam focus will matter - possibly even more than the lumen count (which varies from Mfr to mfr) Established brands, such as Niterider, Light & Motion, etc... will almost always give you a better light pattern and power. It's worth the investment if you commute. I have a Niterider 1500 I use for MTB riding, and on High, it is even a bit brighter than the headlight on my BMW street bike. After I got the 1500 headlight for my MTB, I added auxiliary lights to my BMW! It's only your life at stake - spend $100 - $150 and get a good name brand light with at least 800 lumens and you'll be good.