I am trying to decide if I should buy the 64GB or 128GB version of iPhone 6s+. When I was at Apple Store, the sales told me that if iPhone 7 comes out next year, I can trade n an iPhone 6s+ for about 50%. I just checked http://www.apple.com/shop/browse/reuse_and_recycle . First, I wanted to check how much I could get if I sell an iPhone 5s+ to estimate the trade in cost when 7+ comes out. I cannot find 5s+. Why it is not listed? Then, I checked the current trade in values of 6+ 64GB and 128GB. While we could trade in the 64GB version now at only about 40%, the trade in values of both versions are the same. Why we cannot get more money back having double the memory?