Aliexpress
Click here… to search for Xiaomi MiTU Folding Stroller Platinum on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. Only one coupon available!
Link: Banggood product page
Coupon (274.98 USD): 7bcdf9
(CouponsFromChina.com tip: you should apply the coupon in your cart after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): TTxBG10, BGss8%hl, bgssaff9, AFfbG10, 502C6B, 7d18f7, BGBFCR03, BGCITYADS2019, BGHOMEG12, BGAFF10OFF, bGhOnEy10, BGdragonBoat, BGSS10%SW, bgshOOp10, BgoFErTaSchInA10, BgcLuBofErtA10, BGCuponation10
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi MiTU Folding Stroller Platinum.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).