Xiaomi SWDK FG2020 Dry and Wet Vacuum Cleaner (Banggood, Aliexpress: Rated voltage DC29.6V, Tank capacity 500ML, Size 308*250*1100mm, Battery capacity 2500mAh (the best price with coupon)).
Basically copy coupon, view price history or create e-mail price alert. Do you want to know what the best price is?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. I found coupon for you. Check this out.
Link: Banggood product page
1. ($340.99): 7bcdf9
apply it in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGSWDK299, bgchinafest, BGSWFG, BGSWDKFG, BGSWDK20, aff7off, BGSWKFG, bGpAnDacHeCk, BGHOMEAPP, BGAFF7OFF, BGBWFG2, BGHCLE15, bgshOOp10, BGHome15%, BGHOMEAPP13, BGHOMEA13, BG11SHOP
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for Xiaomi SWDK FG2020 Dry and Wet Vacuum Cleaner is here. The lowest price was: $289.96.
Price records source(s): 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)).