E-Prance via Amazon offers its E-Prance 100ml Cool Mist Aromatherapy Diffuser for $26.99. Coupon code "4O55W74R" cuts that to $19.98. Plus, Prime members bag free shipping. (Non-members can spend $35 or more to qualify for free shipping; otherwise, it costs an extra $5.67.) That's tied with our November mention, $30 off list, and the lowest total price we could find. It works for up to 200 square-feet areas and features auto shutoff and seven color LED lights.