Amazon offers Prime members the Mr. Beams Indoor/Outdoor Motion Sensor LED Lights 2-Pack, model no. MB522, for $16.43 with free shipping. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.67.) That's the lowest total price we could find by $6. Each light features an auto-shutoff, 120 sq. ft. of coverage, and detection range up to 12 feet. This 2-pack requires six C batteries (not included).