Help, advice, & opinion on buying used MBP retina or new MB Air

Hi everyone,

Hope to get more advice from a you pros out there.

I'm going back to school in Jan.
Currently don't have a laptop(windows crap).
Never used an Mac before.
Was Looking into MB Air.

Saw a 1 month old MBP retina on CL for $100(+tax)off.
Doesn't seem like a great steal or anything but he's willing to throw in a copy of Windows.
Comes with remainder or AppleCare.
The end of the day only saving $235 and I don't know how to inspect it when I go see it... what to do?

Help!
Thanks