Can I use Unity Free?

Yes, Unity 5 Personal and Unity 4 Free both work fine with Oculus headsets. Here's the difference between the licenses. http://unity3d.com/get-unity

Using the latest Unity all you now need to do is go to Player settings and check the Virtual Reality option. That's it. Should now work through the Rift. :D

Alright thanks guys. I might start right now building the scene than when I get the gear I would start making the game functions.