it is the model you like and not because it is a good bargain.
The Ellipse has its charm, has its aficionados but is not necessarily the most coveted model from PP. So go for it if YOU like it, and enjot it every time you wear it. But don't buy it just because of the reasonable price.
As for the authenticity, I'm not a speicialist of the Ellipse either, but every detail I look at seems good to me.
Best,
Mike