I have checked all old coupons and price is $146.99 for NICE-POWER R-SPS3020 DC Power Supply 0-30V 0-20A (in Banggood). Just check coupons out (with price alert and history). Best price?
Latest coupon and price update (UTC):
NICE-POWER R-SPS3020 Regulated DC Power Supply 0-30V 0-20A High-Power Output 600W with Smart Temperature Control Overload Protection Compact Portable Digital Calibration Technology for Reliable Performance – EU Plug
Banggood ($146.99)
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. I think you want to know if the price is good. Well, this price is higher than average price ($138.64)
Link: Banggood product page
Price: $146.99
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGe245a9, BGSPRING8OFF, BGHONEYSP, BGESJY8, BGALL8
(I don’t think these’re gonna work, but you can try ’em 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 NICE-POWER R-SPS3020 DC Power Supply 0-30V 0-20A.
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)).