Amazon offers its Prime members the Mr. Beams Wireless LED Motion Sensor Spotlight
in Black, model no. MB390, for $18.12
with free shipping
. (Non-members can spend $49 or more to qualify for free shipping; otherwise, shipping costs $6.85.) That's the lowest total price we could find by $4 and the best price we've seen for this light. It features a waterproof design, 300 lumens brightness, motion detection from 25 feet, up to 400 square feet of coverage, and lens cleaning kit.