Good evening, hope you are well.  Are you interested in the iphone 6?
Yes I am. Is there anything currently wrong with it
There is nothing wrong with it at all.  Excellent condition, looks like brand new.  
Ok, I'd like to buy it but can only do $230
I was really hoping to get $250 for this iphone.  $250 is a great deal for this phone, but I will be willing to part with it for $235.
Ok, $235 sounds totally fair to me