Range 100meters in open area/30meter at home, Size 38mmx 18mmx 100mm, Model DG-R8H Outdoor Sensor for TH11300 TH8380 TH1981 TH8805, Frequency 433MHz, Update Interval 60 Seconds, Power by 2x AAA / LR03.
Just check coupons out (with price alert and history). Do you want to know what the best price is?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
1. ($3.59): BGSAMRTH
you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): aff7off, BGaDmITAd, bgchinafest, BGBFAFF2019, BGCITYADS2019, 2020CNY, BGDG15, BGSAMH, 20%DG422, BGDigoo15%, BGSMOFF, BGDGASG
(probably won’t work, but you can try them out)
Price history and price alert
Price history (for all/most countries) for Digoo DG-R8H 433MHz Wireless Hygrometer Thermometer is here. The lowest price was: $3.39.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).