Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (12.73 USD): Cuponation9
(CouponsFromChina.com tip: you should apply the coupon 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): BGHB218, BGab3fa4, BGd0e188, BGb7f938, BGHU1804, BGbba274, BGMNE01, BG136ec8, BGab0d29, BG5497f1, BGHECARE1, BG4ee866
(there’s a little possibility that old coupon will work)
Price history and price alert
Here is price history (for all/most countries) for Multifunctional Seven-day Mini Rainbow Pill Box.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).