Tenswall via Amazon offers its Tenswall 13.5-oz. Ultrasonic Aromatherapy Essential Oil Diffuser and Cool Mist Humidifier in Natural, model no. TW-501, for $34.99. Coupon code "KPGLL5MP" drops it to $19.94. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, shipping costs $7.19.) That's the lowest total price we could find by $6. It features a 13.5 oz. capacity, two mist modes, seven LED light colors (with steady and rotating modes), four timer settings, auto shutoff, and a 6-foot cord.