You can get ETOPOO Digital Depth for 18.99 USD with coupon (from Banggood). You can create price alert here, copy coupons and view price history. Let’s see what best price is ATM.
Latest coupon code price check (UTC time):
Banggood (18.99 USD)
Banggood warehouse is located in China. I have no active coupons for you right now. Isn’t it too expensive? From what I can see this price is higher than average price (16.71 USD).
Link: Banggood product page
Price: 18.99 USD
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGWDT15, BG76cfa1
(these coupons are old, so probably won’t work)
Aliexpress
Click here… to search for ETOPOO Digital Depth Gauge on Aliexpress
Here are coupons that you can use.
Price history and price alert
Check out price history chart (for all/most countries) for ETOPOO Digital Depth Gauge.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).