Aliexpress
Click here… to search for Xiaomi Mijia Wowcase Bit Box on Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. One coupon is available. Cool!
Link: Banggood product page
Coupon (8.31 USD): BGGines
(CouponsFromChina.com tip: put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop)
Old coupons (from the oldest to the newest): 20tools, 502C6B, e2bcea, XM15TF, 38fdec, BG1534, BG2WOW2, AFfbG10, BGOMG2, BGWowstick2, BG111BB, BGoo1, BGPowerTool15, BG2020NS, BGWOWBT, BG2SB2, BGWowstickFB, BG2MFC, BGherra, BGPTOOL, BGWow101, BGPower09, BGPToo15, BgcLuBofErtA10, BGWOWSK15, BGETS3, BGPower15off, BG931bb3, BG123FBR, BG123F2021, BGPTL088
(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 Mijia Wowcase Bit Box.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).