Read the posts from the last year or so in the "Best $50 headlights" thread stickied at the top of this forum.
I think the Keygos XML-U2 is still available that I found on this thread. It is $39 or less and it is plenty bright for your stated use. It comes with 2 18650 rechargeable Li-ion batteries, a charger, a headmount and a bar mount. You really can't go wrong for the price even if it doesn't quite meet the spec.