Aliexpress
Click here… to search for Xiaomi CatDrive Plus Smart Hard Drive Enclosure on 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 (81.80 USD): AFfbG10
Coupon (84.53 USD): aff7off
(CouponsFromChina.com tip: apply it in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): cf2ac6, e2bcea, TTxBG10, BG3CSUM, bgssaff9
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Price history (for all/most countries) for Xiaomi CatDrive Plus Smart Hard Drive Enclosure is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).