With orders of $25 or more, Amazon offers Prime members the Coleman Micro Packer 100-Lumen LED Lantern, model no. 2000020183, for $4.62 with free shipping. (Non-members can spend $49 or more to qualify for free shipping.) That's the lowest total price we could find by $13. It converts to a flashlight and features a water-resistant design.

Note that this item is part of Amazon's "Add-on program" and can only be purchased with an order of $25 or more.