Are there any "deals" to be had?
Pricing is pretty standard.
Not sure why you'd go with E-Bay when you can walk into a store and buy a PS4 brand new for $400.
I don't want to get to start a war, but if you're having trouble deciding then my basic advice is to get the PS4 unless you are interested in the Kinect features (Cable TV integration etc).
The PS4 is graphically more powerful by roughly 30% but that's already shown to be a significant difference when comparing the same game on both consoles. You can easily Google this. Basically the XBOX ONE has to render at a lower resolution which results in jagged edges (the reason anti-aliasing exists to smooth lines).
Jagged edges can be really annoying expecially when it causes "shimmering" of horizontal lines.