Hello, are you interested in my iPhone 7?
Hi, yes I am, are you a store or is this private party?
I work at a store. I got it as a bonus, but I don't need another phone, so I'm selling it. 
Ahh ok I see. Before I buy it, can you send me the ESID on the phone? You don't have to give it to me now, but before I hand over the money I want to run a check to make sure it's not blacklisted or reported stolen or anything.
I can do that for you. 
Alright, great. Now, I know you're wanting $850 for it, but really I'd like to pay around $500, is there anything you can do for me?
Lowest I can go is $650 with a trade-in.
Trade-in, $650, and you throw in those wireless headphones?
The wireless headphones don't come with the phone, so I'm afraid not. 
Ouch, alright. That's the best I can do I'm afraid. I'll have to keep looking, but thank you for your time.