Hi there 
Hi, how much are you selling the iPhone for?
I'm selling it for 350!
That's strange, that isn't the list price. I'll give you $100 for it.
It isn't? 
Perhaps mine is different than yours
Huh that's interesting, I'll sell it for 300? Is that a better price for you? Do you want more info about the phone?
What condition is it in? Does it come with any other items than just the phone? How long has it been used for?
It looks brand new and in new conditipn
I'll give you $125 for it
It also comes with a case and a screen cover. This is a steal and a on iPhone 6, with extended memory of 64 gigs
200$?
I'll give it for you for 275 and I'll even drive it over to you and I can put warranty on it to make it so if something breaks you can get it fixed for free!
Okay, that's a deal