Aliexpress
Click here… to search for WHDZ MD812 Wood Moisture Meter on 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 (11.70 USD): BGherra
Coupon (12.77 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): TTxBG10, aff7off, bgssaff9, AFfbG10, BGNEMPRO, BGMPB2020, BGAFF10OFF, bGhOnEy10, BG11SHOP
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for WHDZ MD812 Wood Moisture Meter.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).