Only one suggestion: if you accept the $85 be sure to tell him that is the final price and if he arrives thinking that you will discount even more after the two of you have already agreed on a price, then he will go home without the chickens. I'm sure there is a nice way to tell him that if you put some effort into it. Don't let him agree to one price and then expect you to sell them for much less just because he is standing there in front of you.
Extra roosters around here appear to be freebies, and I am sure most of them end up sharing a coop with dumplings and gravy. That's why I only hatch what my own family needs. I'm not putting time and money into raising some stranger's free dinner.