Aliexpress
Click here… to search for Xiaomi Bluetooth Audio Receiver 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 (30.42 USD): BG651551
Coupon (30.42 USD): BGBRPL2
(CouponsFromChina.com tip: apply code in your basket (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): e2bcea, TTxBG10, BG3CSUM, AFfbG10, 502C6B, 0e7f33, FBCOUPON1, BGLOAC1, 13f142, BGa0b145, BGBuscape01
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi Bluetooth Audio Receiver.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).