Basically copy coupon, view price history or create e-mail price alert. Let’s see what best price is ATM.
Product Name: Mi Paipai Wireless Projector, Computer interface: USB interface, Maximum working distance: 10m, Display port: HDMI port + power port, Display size: 149.6×61×12.5 (mm), Net weight on computer: 38.5g, Product color: white, Display net weight: 38.5g, Computer terminal size: 152×60×11.9 (mm)
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):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
1. ($81.41): 00c906
just apply this code 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): 7d18f7, 13f142, 6GSGIT
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for Xiaomi Paipai Wireless Screen Projection Device.
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)).