According to my DB the lowest price is 15.49 USD for 50-300V 20A/100A (in Banggood). Price history, coupons and price alert are available on this page. What is best price?
Latest price update (UTC time):
Banggood (15.49 USD)
Banggood warehouse is located in China. CouponsFromChina software could not find any coupon for this product in Banggood. Low/high price? Hmmm, price is higher than average (which is 15.42 USD right now), so better set price alert down below…
Link: Banggood product page
Price: 15.49 USD
Old coupons (from the oldest to the newest): BGGines, BGM1TOOLS88, BG20236Tool, BGTOOS729
(I don’t think these’re gonna work, but you can try ’em out anyway)
Aliexpress
Click here… to search for KEWEISI AC 50-300V 20A/100A Digital Electricity Meter on Aliexpress
Here are coupons that you can use.
Price history and price alert
Check out price history chart (for all/most countries) for KEWEISI AC 50-300V 20A/100A Digital Electricity Meter.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).