Excommunicate Tratoris has a converted a really nice Primaris Psyker model.
This looks like it was a fairly involved conversion but at the same time, it looks like something that I *MIGHT* be able to do as well. The brown stuff work at the waist is really solid.
Here is a shot of the Games Workshop Primaris Psyker -
Seeing this I am even more impressed by the above conversion. They did a really good job of incorporating several elements from this model on their conversion.