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 (15.23 USD): BGSCM11
Coupon (16.27 USD): BG589b2e
(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): BGwhielabel, BGHolder25, BGc752eb, 13f142, BG10OFFAFF1, BGJUP12, BANGGOODSD, 6GSGIT, BGMOTO478, BG00c906, ADMITAD2212, 2022ACTIESNL, Terence, Tabby20, 2203ActiesNL, BG1efeb0, 8Couponsde, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, BGAUTO22, BGdcbfa8, TTSUMMER8, Cuponation9, BGSCM75
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Baseus 4.7-6.7inch Adjustable Phone Bike Holder is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).