Gamiss offers this Mini Car Humidifier / Essential Oil Diffuser in several colors (Green pictured) for $8.37. Coupon code "JUNENEW20" drops it to $5. Even better, free shipping applies. It plugs into your car's DC port and features a 1.7-oz. water tank that rotates 180°, ultrasonic atomization technology, and automatic shutoff. Deal ends July 22.