Stumbled across this today as i've been continuously checking around for this particular model for awhile.
Locally $349 seems to be about the going price with not many discounts to be had.
Garmin Store
DC Rainmaker Review
I haven't dealt with Gearbest before so taking a punt with them.
Features:
* Garmin’s ELEVATE optical HR sensor for workouts & 24×7 monitoring
* Daily Activity Tracker, with inactivity alerts & Intensity Minutes
* Sleep Tracking
* Stair/Floor counting (barometric altimeter!)
* Smartphone notifications (not just text/call/calendar), Weather Display
* Cardio & Other Activity Modes
* Control of music on your phone
* Garmin VIRB Action Cam control
* ANT+ HR rebroadcasting to other Garmin deices
* Battery Life - Up to 5 days watch/activity tracking mode (24/7 heart rate monitoring, no GPS) or up to 8 hours using GPS
* Running workout modes
* Basic run/walk mode and Virtual Pacer modes
* Move IQ (automatic sport recognition)
* Touchscreen that’s waterproof to 50m
Things to be wary of:
* Doesn't work with external ANT+ sensors e.g. a chest strap HRM.
* HRM not as accurate as a chest strap.
Edit: Updated to reflect the coupon pricing in the comments.
That's a pretty good price, looking broader to US websites as a comparison they are about $280 AUD-ish right now after conversion.