Just check coupons out (with price alert and history). Best price?
Can interoperate with the Aqara multi-functional gateway and other smart devices, Model: DJT11LM, Powered by a CR2032 battery
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):
Price history and price alert
Here is price history (for all/most countries) for Aqara Smart Motion Sensor International [Fast-30].
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)).