nice 3D animation of a tree growing

I need a 3D animation of a tree. from nothing it grows into a full tree with leaves. the animation will be used for video and should be in a format for such. I wil only consider bids from someone who can show me an animation they created. and who will agree to show me a scetch or jpg of what the tree will look like before I assign the project. I will also need the source files so that I can tweek it on my end as needed.