Aliexpress
Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (47.59 USD): BGLMQ15
Coupon (49.27 USD): BGSCM11
(CouponsFromChina.com tip: 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
Old coupons (from the oldest to the newest): 00c906, BG00c906, ADMITAD2212, 2022ACTIESNL, BGCarEle1, 8Couponsde, MVC8SPRING, 8BGwbg2204, BGCarEle3, BGAUTO22, BGdcbfa8, BGfa2cf5, BG8ReviTrage, Cuponation9, 9OFFSUMMER, BGCarEle4, BGcd643e, BGCarEle5, BGd64aa7, BG845979, BGCAR639
(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 Lydsto 100W Car Inverter 12V to 220V.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).