SJCAM Action Camera Dual-Screen SJ4000 AIR 4K 30PFS 1080P 4x Zoom WIFI Waterproof Cam Sports Video Action Cameras.
You can create price alert here, copy coupons and view price history. You probably want to know what is the 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 Hong Kong.
Link: Banggood product page
1. ($52.99): BGf01771
2. ($55.99): BG589dc0
3. ($62.99): BGAMMT03
apply it in your cart after clicking “Proceed to checkout”. Click to copy code and open shop.
Additional Banggood coupons: first page and second page
Old coupons (from the oldest to the newest): BGCAR639, BGLMQ15, BGSCM11, BGNEWYEAR8, BGd1b5ae
(probably won’t work, but you can try them out)
Price history and price alert
Check out price history chart (for all/most countries) for SJCAM SJ4000 AIR Action Camera. The lowest price was: $39.99.
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)).