Hello! Total iPhone n00b here. I'm an Android user currently considering purchasing an iPhone. I am eying a pre-owned 5S; as far as I'm concerned, it's being sold at a pretty fair price ($150) albeit at a pawnshop. What I don't know though is, how can I make sure the phone's legit and no one would suddenly show up my front door saying the phone is theirs. I've checked with our local carriers and it's not on their (IMEI) blacklist. Is there something else I need to do or check before I buy the phone? And no, I don't want to subscribe to a carrier nor would I want to purchase a brand new one (simply because I'm trying to limit my expenses right now). In short, I'd like to try out the iPhone without breaking my bank.