Standard USB Interface / Flexible / Dismountable / Pocket Size / Mute Fan.
Just check coupons out (with price alert and history). Do you want to know what the best price is?
Aliexpress
I could not find it on Aliexpress. Click here to search by yourself.
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($6.01): BGAFF10OFF
2. ($6.01): bGhOnEy10
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): e2bcea, TTxBG10, BG3CSUM, AFfbG10, 502C6B, BGBFAFF2019, BGCITYADS2019, BGdragonBoat
(there’s a little possibility that old coupon will work)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Flexible USB Fan. The lowest price was: $0.99.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).