You can create price alert here, copy coupons and view price history. What is best price?
Lamp Life 30, External Subtitle Supported Yes, Throw Ration 0.233: 1, Video Formats avi/mpg/dat/vob/div/mov/mkv/rm/rmvb/mp4/mjpeg/ts/trp/wmv/asf/flv, RJ45, Picture Formats JPG/PNG/BMP, HDMI, 4: 3, Display type DLP, USB, WiFi, Brand JMGO, Image Size 100 – 500 inch, SPDIF, Contrast Ratio 1500: 01: 00, Image Scale 16: 9, WIFI 802.11 b/g/n/ac, Built-in Speaker Yes, Projection Distance 0.1 – 0.5m, Bluetooth Bluetooth 4.0, Brightness 1500LM, DVB-T, Bluetooth, Material Aluminum Alloy, Power Supply 100-240V, Noise (dB) 30dB, 3D Yes, Speaker, Xbox, Compatible with Sony PS4, Native Resolution 3840 × 2160, Function 3D, Model X3, Interface 3.5mm Audio, Audio Formats mp3/aac/wma/rm/flac/ogg/mpeg audio/ac-3/dts/mpeg-1/amr/cooker/pcm/ogg vorbis, DVB-T Supported No, 000h, Resolution Support 4K
Aliexpress
There’re some similar (or not) items on Aliexpress
Click here to search by yourself. Here are coupons that you can use.
Latest coupon and price update (UTC):
Banggood
Banggood warehouse is located in China. There is one coupon right now! Check this out.
Link: Banggood product page
1. ($1319.99): 7bcdf9
apply it in your 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/5cd
Old coupons (from the oldest to the newest): aff7off, BGJGX3, BGaDmITAd, bgchinafest, BGCITYADS2019, bGpAnDacHeCk, BGMPB2020, Email5, bGhOnEy10, BGdragonBoat, BGAFF7OFF, bgshOOp10, BgoFErTaSchInA10
(these coupons are old, so probably won’t work)
Price history and price alert
Price history (for all/most countries) for JmGO X3 DLP Projector is here.
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)).