Aliexpress
Click here… to search for Xiaomi 8H Air U-Shape Pillow on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (22.16 USD): BGTY742TRL
(CouponsFromChina.com tip: coupon code has to be applied in shop’s cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): 0e7f33, BGYS636, BGTS204, FBCOUPON1, BGTRIP01, BGCuponation10
(there’s a little possibility that old coupon will work)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi 8H Air U-Shape Pillow.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).