At the budget the OP is looking at spending, ATMOS is either a waste of time or simply not available.
The Panasonic that was mentioned is probably the cheapest 'ATMOS' bar, but while it can decode ATMOS DTS:X etc I doubt it can reproduce anything close to what you'd hope. As in example, it only has 3 x full range drivers (not a driver + tweeter arrangement or even beam drivers that can fire the sound around the room) I wouldn't expect much in the way of performance - let alone ATMOS.
If you're spending 2K on a sound bar it can sound pretty good if you have a flat ceiling and square walls around you - if not, it's fairly 'meh'.