Brand Name JmGo.
You can create price alert here, copy coupons and view price history. What is best price?
Aliexpress
There’re some similar (or not) items on Aliexpress
You can use link bot to get even lower price:
Click here to search by yourself. 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 available! Pretty cool, huh?
Link: Banggood product page
1. ($504.89): BGAProjector
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 and https://couponsfromchina.com/short/i1u
Old coupons (from the oldest to the newest): BGAFF7OFF, BGJGEXP, 7bcdf9, BGissam81564, BGProjectors
(these coupons are old, so probably won’t work)
Price history and price alert
Check out price history chart (for all/most countries) for JMGO Explorer Projector. The lowest price was: $389.99.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood and Aliexpress (only if product name will be the same as on Banggood and I will post it on social media though, so it’s more like Banggood price alert)).