Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (48.66 USD): hoNEYbGdeAlS
Coupon (49.72 USD): BG00c906
(CouponsFromChina.com tip: paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGmodule12, 7d18f7, BGVDay10%off, bGhOnEy10, bgshOOp10, BgcLuBofErtA10, BGRUMB15, BGAFF10OFF, 13f142, BGHONEY2110, 00c906, Terence, Tabby20, 2203ActiesNL, BG1efeb0, 8Couponsde, MVC8SPRING, 8BGwbg2204, tRaDetRaCKeR, 8wEbgaInS5, pROMo8cuPoN
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Digital Power Supply Case S06A For RD6006 RD6006W.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).