Aropey via Amazon offers the Aropey Aroma Essential Oil Diffuser for $15.99. Coupon code "OMC9KU44" drops it to $8.95. Plus, Prime members bag free shipping. That's $4 under last week's mention, $31 off, and the lowest price we could find. Features include a 70ml water tank, 7-color LED light, and automatic shut off. Deal ends October 17.