Rated voltage: DC 7.2V, Battery runtime: Around 24min, Max Suction: Around 5000pa, Dust holder capacity: 100ml, Charging time: 3h(5V/2A charging), Battery capacity: 7.2V4000mAh (28.8Wh), Rated power: 80W, Input: 5V/2A, Dimensions: 312mm(Length): 73mm(Diameter).
Go down and check coupons out. Remember to check price history if it is available. Let’s see what best price is ATM.
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. ($79.51): BGCarEle4
2. ($85.12): Cuponation9
3. ($87.93): BG00c906
coupon code has to be applied in shop’s 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/i1u
Old coupons (from the oldest to the newest): BGAutos, BG70MAI18, BGCARELEC, BG70maiCleaner, BGAFF10OFF, BGCuponation10, 13f142, BGHONEY2110, BG10OFFAFF, BGwhielabel, BG10OFFAFF1, BANGGOODSD, 00c906, ADMITAD2212, 2022ACTIESNL, BGCarEle1, MVC8SPRING, 8BGwbg2204, BGCarEle3, BGAUTO22, BGdcbfa8, DealBGimpact
(these coupons are old, so probably won’t work)
Price history and price alert
Here is price history (for all/most countries) for Xiaomi 70mai Portable Wireless Car Vacuum Cleaner. The lowest price was: $39.99.
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)).