Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. I found coupon for you. Check this out.
Link: Banggood product page
Coupon (23.88 USD): BG00c906
(CouponsFromChina.com tip: just apply this code 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): AFfbG10, BGTS785, BGTS204, BGAFF10OFF, BGTT10, bGhOnEy10, BGdragonBoat, BGCAMP01, bgshOOp10, BgoFErTaSchInA10, BgcLuBofErtA10, BGZPBC15, BGHBHJ106, BGTY704CP, BGCuponation10, BGHONEY2110, BG10OFFAFF, BGwhielabel, 13f142, BG10OFFAFF1, BG4d9120, BGAlerabatod, 00c906, BGe46870, BG7280ff, Tabby20, 8Couponsde, BG36e006, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, BG2bb7a1, BG5d2ea4, BG8ReviTrage, Cuponation9, BG073996, BGc363fd
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi YUNMAI Waterproof Waist Bag.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).