Aliexpress
Click here… to search for Xiaomi Aquaponics Ecosystem Fish Tank on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (125.99 USD): AFfbG10
Coupon (125.99 USD): affbg10
Coupon (130.19 USD): aff7off
(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): 502C6B, c98553, e2bcea, 49b91a, vipupgrade8, TTxBG10, bgssaff9, BGFISH999, BGGF79, BGOWE79, BGBFAFF2019, BGCITYADS2019, BGBGHFRI15, BGTANK889
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Xiaomi Aquaponics Ecosystem Fish Tank is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).