Just check coupons out (with price alert and history). What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Suction: 2800Pa, Power consumption: 75W, Input: AC 100 – 240V, 50 / 60Hz, 2.0A, Battery Capacity: 600mAh, Cleaning speed: 2.5min / square meters, Noise level: 65db
Price history and price alert
Here is price history (for all/most countries) for Alfawise WIN660 Robotic Window Cleaner [Fast-23].
Price records source(s): Gearbest
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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)).