I currently have the iPad Mini with Retina Display 64gb and cellular. I'm looking to upgrade to the 128gb model. I found an iPad Air 128gb non-cellular for $650 and an iPad Mini with Retina Display 128gb non-cellular for $475 on Craigslist. Both are in like new condition, though the seller for the iPad Mini says he does not have the box/accessories. I'm not sure which is the better deal here. I don't think anyone will trade his/her iPad from a higher capacity to a lower capacity, so I think I will have a better chance if I sell my iPad Mini for $600. Any advice is greatly appreciated.