Aqara Smart Door Lock NFC Card (Banggood, Aliexpress: Weight: 4g, Type: CPU Card, Brand: Aqara, Each Aqara smart door lock supports up to 25 NFC cards, Size: 26mm*42mm*3.5mm, Material: Epoxy (the best price with coupon)).
Price history, coupons and price alert are available on this page. What is the 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 coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($11.82): Cuponation9
2. ($11.95): TTSUMMER8
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGaef37b, ADMITAD2212, BGSmart6, BGc40e8c, 8Couponsde, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN, BGJUNEGSG9
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Aqara Smart Door Lock NFC Card is here. The lowest price was: $7.99.
Price records source(s): 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)).