Hobby Tool Supply via Amazon offers its Amazon prime members the SE Wireless Motion Sensor Light, model no. FL8403-10, for $8.32 with free shipping. (Non-members can spend $25 or more to qualify for free shipping; otherwise, shipping costs $5.14.) That's the lowest total price we could find by $4, although we saw it for $1 less in January. It uses infrared technology to sense both motion and heat and features 10 LEDs. It operates on three AA batteries (not included).