Anker, producer of a lot of your favorite charging gear, has its own line of flashlights now, and this 2-pack of LC40's down to $19, its best price.

These are the cheapest models in the flashlight line, but they’re IP65 dust and water resistant, but actually doesn’t include a rechargeable battery. However, you can run it on three AAAs or a single rechargeable 18650 battery, which are cheap and easy to find.