We have IPhones and when my mom was visiting in Europe, we got a simple International plan on my phone so we had contact. It was not that expensive and we only spoke a couple of times. You can remove the feature when you get back home.
As for IPhones, we recently sold our old ones on CL for $100 each within 12 hours. Nothing was wrong with them, we just all upgraded. Make sure you get a legit deal if you do that so you are not scammed. I am not a big CL fan because of all the scammers but it has worked for us a couple of times.
Is your nephew asking you to buy the phone for him and he is not reimbursing you? Is it a gift? See what he is willing to pay.