LightInTheBox offers the Mini Cree Q5 LED Tactical Flashlight for $7.99. Coupon code "SO4897464" cuts it to $3.99. With free shipping, that's $4 off list and the lowest price we could find. It features 500 lumens of brightness, waterproof Level IPX-3 and IPX-4, and a range of 328 to 653 feet.
Note: Uncheck "Add Shipping Insurance to your order"during checkout to avoid the 49-cent fee.