Aliexpress
Click here… to search for Digoo DG-C9 Alarm Temperature Clock on 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 (12.59 USD): BG10OFFAFF1
Coupon (12.99 USD): 13f142
(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): BGIRU59, AFfbG10, BGC9499, BGBFAFF2019, BGC9RA, BGDigoo15%, BGBWJP1, BGDDDQ, BGDDDPP, BGDGDD, BGDGCCC, BGFPRBW, BGDDCC, BGVDay10%off, BGDG15, BGdigoo15, BGDG110, BGAFF10OFF, BGXXSAJP, bGhOnEy10, 20%DG422, BGDCDNZJP, BGCCCDDJP, BGCCDDJP, BGSS10%SW, BGdragonBoat, bgshOOp10, BGHome15%, BGHOMEA15%, BgcLuBofErtA10, BGCuponation10, BGHONEY2110, BG10OFFAFF, BGwhielabel
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for Digoo DG-C9 Alarm Temperature Clock is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).