Aliexpress
Click here… to search for Xiaomi FREETIE Slippers Black on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (11.75 USD): BGRSHOES
(CouponsFromChina.com tip: apply code in your basket (cart) after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): 502C6B, TTxBG10, 42685c, 689daa, 759102, 5472b5, 715bfc, 97c2b3
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Xiaomi FREETIE Slippers Black is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).