I have just checked coupons. The lowest price I could get is $14.99 for XY-UDP Digital USB DC Converter (in Banggood). Just check coupons out (with price alert and history). What is the best price?
XY-UDP Digital USB DC Converter CC CV 0.6-30V 5V 9V 12V 24V 2A 15W Power Module Desktop Adjustable Regulated Power Supply
Latest coupon and price update (UTC):
Banggood ($14.99)
Banggood warehouse is located in China. Coupons for XY-UDP Digital USB DC Converter? Nope, there’re no coupons in Banggood. But wait a sec… Is it a good price? Maybe there’re no more promotions for this item, because current price is higher than average (which is equal $12.99)
Link: Banggood product page
Price: $14.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BG589b2e, BG3aa3e2
(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
Here is price history (for all/most countries) for XY-UDP Digital USB DC Converter.
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)).