Basically copy coupon, view price history or create e-mail price alert. What is best price?
Memory 8 cores / running memory 2G / 16G storage memory, Power Voltage DC 12V/1.5A, Support playback Smooth playback of 1080P video, Working temperature -20°C ~60°C, Name IPS screen hanging Android system display, Display 12.5-inch / 16: 9 high-definition digital screen, Resolution 1920*1080, FM Support FM transmitter, Operating system Android 9.0, Internet Phone hotspot / WiFi
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. One coupon is available. Cool!
Link: Banggood product page
1. ($298.44): BGAUTO22
apply it 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): BGCarAud1, BGCarAud3
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Do you need price history chart (for all/most countries) for 12.5 Inch Android 9.0 Car Rear Seat Headrest Monitor? There we go.
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)).