Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (165.59 USD): BGBFDAY8
(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): BG589b2e, BGAUGUST8, BGCAPITALOS8, BGCOUPERT8, BG8FORMULAMX
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Here is price history (for all/most countries) for Xiaomi Geometry Aquaponics Ecosystem Aquarium 5W.
Price records source(s): Banggood
Click on image to enlarge.
You can set price alert (for Banggood).