When I was updating this page, then coupon price was $29.99 for FNIRSI DSO153 2in1 Portable Digital Oscilloscope Signal Generator 1MHz 5MSa/s (in Banggood). Price history, coupons and price alert are available on this page. Best price?
FNIRSI DSO153 2in1 Portable Digital Oscilloscope Signal Generator 1MHz Bandwidth 5MSa/s Sampling Rate Compact Electronics Repair Tools 1000mAh Battery USB Charging Diverse Waveforms – Upgrade
Latest coupon code price check (UTC time):
Banggood ($29.99)
Banggood warehouse is located in China. There are no coupons available at this moment in Banggood. Isn’t it too expensive? From what I can see this price is higher than average price ($27.82).
Link: Banggood product page
Price: $29.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG32759c
(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
Check out price history chart (for all/most countries) for FNIRSI DSO153 2in1 Portable Digital Oscilloscope Signal Generator 1MHz 5MSa/s.
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)).