TV 2.4G Wireless WiFi Mirroring Cable Adapter Dongle (Banggood, Aliexpress: Interface: HDMI-COMPATIBLE/USB, Model: G2, Operation System: LINUX, , Power Supply: 5V 1A, Size: About 58×15.3mm/2.28×0.60″, Material: ABS, CPU: AM8252B, HD Video Decoder: 1080p 60fps, DDR: DDR3 128mm (the best price with coupon)).
You can create price alert here, copy coupons and view price history. Let’s see what best price is ATM.
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($18.79): BG589b2e
2. ($18.79): BGProjcc
put item in your cart and apply coupon code there after clicking “Proceed to checkout”. Click to copy code and open shop.
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/feV
Old coupons (from the oldest to the newest): BGProj
(I don’t think these’re gonna work, but you can try ’em out anyway)
Price history and price alert
Check out price history chart (for all/most countries) for TV 2.4G Wireless WiFi Mirroring Cable Adapter Dongle. The lowest price was: $13.99.
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)).