1x User Manual, 1x Adapter, Package Contents: 1x diffuser, 1x Remote control.
Just check coupons out (with price alert and history). What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Price history and price alert
Do you need price history chart (for all/most countries) for Aroma Diffuser 550ml Humidifier? There we go. The lowest price was: $16.99.
Price records source(s): Gearbest
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).