Is there any character option to gain teleport (or any improved version) or greater plane shift, as an at will usage, other than racial ability? 

I'm not really looking at items, except as a last resort. All official material suitable, but no extreme TO, please. 

The goal is ideally to plane shift at will, accurately to the desired destination. Doing a two step plane shift and teleport is fine if the greater plane shift cannot be obtained.