Help: need to random position mc's without overlapping

Tried searching for this every where but no luck.
Can someone please tell me how do can I position around 50 dynamic create movieclips from the library on the stage without overlapping.

I did the random x and y but they end up overlapping, i assume i have to do it with the hitTestObject, but eventually i will have 7 layers with 50mc’s on each stage that need to be positioned randomly without overlapping and it will become processor heavy to test these objects.

Anyone have any suggestions? Maybe a grid or something?