I've been reading posts for a couple of days now, and am not seeing much for flashlight / headlights using NiMh AA cells. All my headlamps use AA's so I really want to stick with that format.

What is the advantage of the 18650 cells?

This will be my 1st foray into road bike (or any actually) night riding - the roads and paved trails are mostly unlit, with a nice variety of foxes and deer to avoid.

Looking for suggestions, threads, ect. to help refine my choices. Seems that 200 lumen is the minimum recommended here for this type of ride.

Also would really really like to keep cost down to $50 or less if possible.

Thanks!