Aliexpress
Click here… to search for 3x Aqara E1 Window Door Sensor Zigbee 3.0 [EU] on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in Europe 
. I don’t know if this is a good price – number of records in my database is too low!
Link: Banggood product page
Coupon (45.07 USD): tRaDetRaCKeR
Coupon (45.07 USD): 8wEbgaInS5
Coupon (45.07 USD): pROMo8cuPoN
(CouponsFromChina.com tip: apply it in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGAQA929, BGa176fe, BGSmart6, MVC8SPRING, 8BGwbg2204
(these coupons are old, so probably won’t work)
Price history and price alert
Well, you won’t see price history chart, coz we have only 1 database record for this item (and price was 33.66 USD).
You can set price alert (for Banggood).