Aliexpress
Click here… to search for Thundeal YG550 1080P Projector Android 9.0 1/16GB on Aliexpress
Here are coupons that you can use.
Latest price update (UTC time):
Banggood
Banggood warehouse is located in China.
Link: Banggood product page
Coupon (244.39 USD): BG589b2e
Coupon (244.39 USD): BGProjcc
(CouponsFromChina.com tip: apply code in your basket (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): BG0db549, BGProj, BGSaleFeb8, BGSaleAD, BGMARCHSALE
(these codes were not working in latest coupon update, but you can check them out anyway)
Price history and price alert
Price history (for all/most countries) for Thundeal YG550 1080P Projector Android 9.0 1/16GB is here.
Price records source(s): Banggood
Click on image to enlarge. 
You can set price alert (for Banggood).