It would be interesting to hear your thoughts on why you are switching back - where has the android/S7 fallen short for you?
Just had a quick look on trade me, I reckon close to $500 would be easily obtainable if put to auction (assuming near new condition).
The Galaxy S7 Edge has been a very good handset probably the best Android unit ( I hope my wife does not read this) I have owned/used. I was for a very long time a Mac user I have returned to using an iMac as my main PC. I also have an iPad and Apple TV and considering a MacBook. The iPhone just simple works better with those devices.