According to my DB the lowest price is $20.99 for XY6020L 6-70V CNC Adjustable Stabilized Voltage Power Supply Buck Module (in Banggood). Price history, coupons and price alert are available on this page. Best price?
Latest price update (UTC time):
XY6020L 6-70V CNC Adjustable Stabilized Voltage Power Supply Constant Voltage Constant Current 20A/1200W Buck Module – Set
Banggood ($20.99)
Banggood warehouse is located in China. I’m afraid that there’s no working coupon in Banggood. I think you want to know if the price is good. Maybe there’re no more promotions for this item, because current price is higher than average (which is equal $20.75)
Link: Banggood product page
Price: $20.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
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
Here is price history (for all/most countries) for XY6020L 6-70V CNC Adjustable Stabilized Voltage Power Supply Buck Module.
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)).