Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China. I don’t think there is an active coupon right now – at least in my database.
Link: Banggood product page
Price: -3 USD
It looks like this item is out of stock in Banggood. If you found it then please send me the link. I will replace it.
Click here to search on Banggood!
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k
Old coupons (from the oldest to the newest): BGAProjector, BGDBLSPR, BGDBMP44, BGprtecmundo, BGDBMPFPK, BG7bc77b, BGDBJR, BGProj, BGcb4ca8, BG589b2e, BGMARCHSALE
(sometimes old coupons work, so you can check them out (this site checks them on every price update))
Price history and price alert
Price history (for all/most countries) for Dangbei Mars Pro 4K Projector ALPD Laser 3200 ANSI 4/128GB is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).