According to my DB the lowest price is $39.99 for FNB48 USB Tester Voltmeter Ammeter with Bluetooth (in Banggood). Check coupons or create price alert down below. Do you want to know what the best price is?
Monitor current: 0~6.5A, Monitor current resolution: 0.00001W, Monitor voltage resolution: 0.00001V, , Monitor current resolution: 0.00001A, Material: ABS, Monitor voltage: 4~24V, Monitor current accuracy: ±（0.5%+2）, Monitor voltage accuracy: ±（0.2%+2）, Monitor current accuracy: ±（0.5%+2）, Monitor power: 0~156W
Latest coupon code price check (UTC time):
Banggood ($39.99)
Banggood warehouse is located in China. So I have checked for active coupons (all category coupons and old ones), but there was no working coupon in Banggood. Price? Well, this price is higher than average price ($35.59)
Link: Banggood product page
Price: $39.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG8OFFCOUPON, BGGines, BGM1TOOLS88, BG20236Tool, BGTOOS729, BG8FORMULAMX
(there’s a little possibility that old coupon will work)
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 FNB48 USB Tester Voltmeter Ammeter with Bluetooth? 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)).