Good camera stabilization requires fast response to external disturbance. Currently all stat-of-art 3-axis gimbals use 3 brushless motors for each axis; they range from very high end ones that work with Red Epic camera for the filming industry to popular recreational GoPro gimbals.
Brushless gimbal motor based approach is more costly to build than alternatives.
A low cost approach is mechanical type using ball bearing without any motor or battery, such as solidLUUV. A mechanical gimbal would suffer from inertia stabilizing the camera when there is quick change of directions.
Various types of low cost $55 motorized rotating mount, not using brushless motors, does not have fast enough response to stabilize disturbance when in motion, is also calling itself a stabilizer.
Recently there is a novel smartphone "gimbal", Snoppa M1, that combines the designs of mechanical gimbal and motorized rotating mount to achieve an ultra-affordable design at $59*. Although it stabilizes much better than a human hand, it still inherits limitations of its forebearers. Also, holding horizontal it’s 3-axis device; holding vertical it’s 2-axis device and will have similar issue of a two axis gimbal. The nicely made campaign commercial video gives viewer the impression that it could stabilize well chasing kids or dogs like a 3-axis brushless gimbal does.
An easy effective way to check real performance of any gimbal is ask for an elevator test demo video, rotating the gimbal in all 3 dimensions in front of mirror which cannot be faked. If the video shows vibration, then there will be vibration problems when later actually using it.