LightInTheBox offers this Tactical 2,000-Lumen Cree Q5 LED Zoomable Waterproof Flashlight for $7.91. Coupon code "SO4897464" cuts it to $3.91. With free shipping, that's $2 below the best price we could find for a similar flashlight elsewhere. It features three modes, adjustable focus, and non-slip grip. Deal ends October 20.
Note: Uncheck "Add Shipping Insurance to your order" during checkout to remove the 49-cent fee.