I have just checked coupons. The lowest price I could get is 326.59 USD for External Car Air Conditioner (in Banggood). It is from European warehouse! Basically copy coupon, view price history or create e-mail price alert. What is best price?
Latest price update (UTC time):
Banggood (326.59 USD)
Banggood warehouse is located in Europe 
. Is it a low price? There’s only 1 record in my database, so I have no idea if the price is OK. You can use 3 active coupon codes for this product!
Link: Banggood product page
Price without coupon: 354.99 USD
Coupon (326.59 USD): BGSPRING8OFF
Coupon (326.59 USD): BGHONEYSP
Coupon (334.99 USD): BGAMMT03
(CouponsFromChina.com tip: paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BG8651cd, BGLMQ15, BGSCM11, BGNEWYEAR8
(these codes were not working in latest coupon update, but you can check them out anyway)
Aliexpress
Click here… to search for Hcalory 24V External Car Air Conditioner [EU] on Aliexpress
Here are coupons that you can use.
Price history and price alert
It doesn’t make sense to generate price history chart, because there is one price record which is: 298.19 USD.
You can set price alert (for Banggood).