Just to make sure, if you're worried about performance impact from using too many layers, don't be. Number of layers shouldn't affect performance. In fact, moving all the objects through events rather than letting them sit still on their own layer would probably be less efficient.
That said, depending on what you're using to move the character, you can possibly use the character's movement speed and angle of motion to nudge objects in the opposite direction at different rates. E.g. something like,
Character is moving
--> move Object A [Character.Speed/2] at angle [Character.Angle+180]
--> move Object B [Character.Speed/4] at angle [Character.Angle+180]
This means Object B will travel at half the speed of Object A in the opposite direction that the character is moving, thus making a sort of parallax effect.
You can also have a look here at Somebody's effects, namely the Seamless and Scroll effects. They can be used to achieve similar things, albeit per object.