Use passive IR to detect what is moving, EU version, 868.4 MHz.
Go down and check coupons out. Remember to check price history if it is available. You probably want to know what is the 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):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
1. ($42.61): BGd0b05d
apply code in your basket (cart) after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/i1u
Old coupons (from the oldest to the newest): elec, AFfbG10, BGVDay10%off, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BgoFErTaSchInA10, BGELIG0920, BgcLuBofErtA10, BGCuponation10, 13f142, BGHONEY2110
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for NEO Coolcam NAS-PD02Z PIR Motion Sensor EU is here. The lowest price was: $22.99.
Price records source(s): Gearbest, Banggood
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)).