Aliexpress
Here are coupons that you can use.
Latest coupon code price check (UTC time):
Banggood
Banggood warehouse is located in China. There is one coupon right now! Check this out.
Link: Banggood product page
Coupon (280.58 USD): 13f142
(CouponsFromChina.com tip: 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
Old coupons (from the oldest to the newest): Wholesale20, wholesale20, Email5, 7d18f7
(you can check these old coupons out, but these probably won’t work)
Price history and price alert
Price history (for all/most countries) for HUAXU3D X1 3D Printer is here.
Price records source(s): Gearbest, Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).