Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. You can get coupon down below.
Link: Banggood product page
Coupon (78.53 USD): BGCarEle4
(CouponsFromChina.com tip: apply it in your 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): BGfc41d0, BG6e27c5, BG8ReviTrage, Cuponation9, 9OFFSUMMER
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Here is price history (for all/most countries) for 60HZ Solar Pure Sine Wave Power Inverter 1500W 12V To 220V.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).