Aliexpress
Click here… to search for Xiaomi MDZ-ZB-DE AI Portable Bluetooth Speaker on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. There is one great coupon!
Link: Banggood product page
Coupon (25.40 USD): BGBuscape01
(CouponsFromChina.com tip: you should apply the coupon in your cart 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): fba5dc, e19855, c81c41, 60bb88, 55XMBT, TTxBG10, 25XMS, BGXM158, aff7off, BG3CSUM, BGIN58, bgssaff9, BG10AIRXM, AFfbG10, affbg10, 502C6B, BGBINKUPON158, BGCNXM7, BGXMAI99, 0e7f33, EARSP11, FBCOUPON1, BGLOAC1, 13f142, 451feb
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi MDZ-ZB-DE AI Portable Bluetooth Speaker.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).