Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (18.21 USD): BGHOMEA15%
Coupon (18.42 USD): FBCOUPON1
Coupon (20.42 USD): 13f142
(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): CT12, FT129, FT999, vipupgrade8, 1888CODE, 0404digoo, 99DGFT, a2fsrf, alibuy2a, a2fsrg, 1964CODE, BGDigoo15%, BGDGFT999, BG20COOP, BGFT999, AFfbG10, BG95DG, affbg10, BGKT3566, BGFT2103PL, BGM995FF, BGTY2K, BGFT149, 0e7f33, BGDG15
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Digoo DG-FT2103 Digital Cooking Thermometer is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).