I have checked all old coupons and price is $16.99 for Sonoff POW Elite 16A Smart Wifi Power Meter Switch (in Banggood). Check coupons or create price alert down below. What is the best price?
Casing Material: PC V0, Input/Output: , POWR316D: 100-240V~50/60Hz 16A Max, Wi-Fi: IEEE 802.11 b/g/n 2.4GHz, Model: POWR316D/POWR320D, Product type: Smart Power Meter Switch, POWR320D: 100-240V~50/60Hz 20A Max, Brand: Sonoff, Color: White, Dimension: 98×54×31mm
Latest coupon code price check (UTC time):
Banggood ($16.99)
Banggood warehouse is located in China. I have no active coupons for you right now. Is it cheap? Good price! It’s lower than average one ($18.03)!
Link: Banggood product page
Price: $16.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGHU2510, Cuponation9, BGHU2515, BG8ReviTrage, BGc99ed5, BG583659, BG89a7ae
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Price history and price alert
Do you need price history chart (for all/most countries) for Sonoff POW Elite 16A Smart Wifi Power Meter Switch? There we go.
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)).