Just check coupons out (with price alert and history). Let’s see what best price is ATM.
Voltage (V): 24V Current (mA): 650mA Input Voltage: 220V Connector Type: EU plug Cord Length: 1.7m Water Tank Capacity (ml): 300ml Application Area (sq.m.): 45
Aliexpress
I could not find it on Aliexpress. Click here to search by yourself.
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Price history and price alert
Price history (for all/most countries) for GDAS 2509EU Aroma Diffuser 300ml Humidifier is here.
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)).