OpenCV and Android with Unity3D

I'm trying to integrate OpenCV or EmguCV with Unity for an Augmented Reality project. I have experience with Unity, know how to program in C#, not really Javascript, but now I want to learn OpenCV with Augmented Reality and the only easy solution is Unity. I have been searching and trying to create plugins for days, the only solution I've found is the [OpenCV for Unity Plugin][1] but it is simply too expensive for me. So can anyone point me in the right direction, that compatible with Android. Thanks in advance. [1]: https://www.assetstore.unity3d.com/en/#!/content/21088