I have had an iPad Mini which I ordered at the onset when they were released last year. It is my constant companion and I am beyond satisfied with this unit. But, in two days I will be receiving an iPad mini retina. I spent $539 to buy this unit and the resale value is somewhere around 250. Is the 16 gig Wi-Fi plus LTE black unit. How to or what is the best way to trade it for someone's ipad 3 or 4 wifi only version?