Aliexpress
Click here… to search for X1 Tuya WiFi Electronic Smart Door Lock on Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (65.99 USD): BGe3aa58
(CouponsFromChina.com tip: coupon code has to be applied in shop’s 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): BGSaleFeb8, BG610fb1
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Here is price history (for all/most countries) for X1 Tuya WiFi Electronic Smart Door Lock.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).