Basically copy coupon, view price history or create e-mail price alert. Best price?
Model: G26, Brand: Mirascreen, Definition: 4K/XDR, Decoding chip: flagship thousand yuan chip, Color: White/Black, Fluency: Upgrade SR signal enhancement, Support frequency band: 2.4G/5G dual frequency, Horizontal and vertical screen switching: support, Name: Display Dongle, Screen projection: support, Projection mode: dual mode
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. There is one coupon available! Pretty cool, huh?
Link: Banggood product page
1. ($43.23): BG589b2e
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/5cd
Old coupons (from the oldest to the newest): BGProj
(system checks these coupons on every price check (like once per 24 hours), but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Mirascreen G26 2.4G/5G Wireless Dongle 4K is here.
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)).