Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (12.60 USD): Cuponation9
Coupon (12.74 USD): TTSUMMER8
(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): 502C6B, vipupgrade8, ML15%Pro, BGKM666, BGSR15, bgshOOp10, bGhOnEy10, BGHB20, BgoFErTaSchInA10, BgcLuBofErtA10, BGCLUBOFERTA10, BGAFF10OFF, 13f142, BGCuponation10, BGHONEY2110, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BANGGOODSD, 6GSGIT, BGHealth06, 2022ACTIESNL, BGHB218, 2203ActiesNL, BGHECARE1, BG4ee866
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Here is price history (for all/most countries) for Kemei KM-666 Mini Electric Trimmer.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).