Basically copy coupon, view price history or create e-mail price alert. What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Battery Capacity: 3200mAh, APP Control: Yes, Voltage: 110-240V, Charging Time: about 4h, Suction Adjustment: 4mode, Battery Type: Li-ion battery, Power: 40W, Working Time: 110min, Self Recharging: Yes, Water Tank Capacity: 250ml, Suction: 2100Pa, Dust Box Capacity: 550ml, Brand: Xiaomi Mijia, Noise: 72dB, Climb Capability: 2cm, Model: 2C, Voice Control: Yes(Only supports Chinese version)
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($323.99): BGwhielabel
2. ($329.99): BGCNXM2C
you should apply the coupon 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
Price history and price alert
Here is price history (for all/most countries) for Xiaomi Mijia 2C Robot Vacuum Cleaner.
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)).