You can create price alert here, copy coupons and view price history. Best price?
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Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
1. ($656.99): BGBFAFF2019
2. ($678.89): aff7off
3. ($678.89): bgchinafest
paste coupon code in your cart and click Apply after clicking “Proceed to checkout”. Click to copy code and open shop)
Exclusive Allowance Coupons: https://bit.ly/3xWgD9k and https://couponsfromchina.com/short/5cd
Old coupons (from the oldest to the newest): BGaDmITAd, BGCITYADS2019
(probably won’t work, but you can try them out)
Price history and price alert
Price history (for all/most countries) for XGIMI CC Aurora Projector Black is here.
Price records source(s): Gearbest, 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)).