Aliexpress
Click here… to search for Bakeey B57 Smartwatch on 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 (29.71 USD): BGc70579
Coupon (29.71 USD): BGbf11dd
(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, TTxBG10, band10, 2019SPEDM, BG3CSUM, AFfbG10, BGB57, BGBK15, BGB5718, BGBAK15, BG18B57, 935D63, BGCuponation10, BG3072fe, BGWRIBAND10, 6GSGIT, BG51f436
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Bakeey B57 Smartwatch is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).