I have just checked coupons. The lowest price I could get is $209.99 for NanoVNA-F V3 4.3 inch LCD 1M-6GHz Vector Network Analyzer (in Banggood). You can create price alert here, copy coupons and view price history. What is best price?
NanoVNA-F V3 4.3 inch LCD 1M-6GHz Vector Network Analyzer, Shortwave Analyzer MF HF VHF UHF Talent Nanovna-F Antenna Analyzer
Latest price update (UTC time):
Banggood ($209.99)
Banggood warehouse is located in China. CouponsFromChina software could not find any coupon for this product in Banggood. What about the price? Good price! It’s lower than average one ($221.13)!
Link: Banggood product page
Price: $209.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG624641, BG4b3a27
(you can check these old coupons out, but these probably won’t 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 NanoVNA-F V3 4.3 inch LCD 1M-6GHz Vector Network Analyzer? 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)).