I figured what Grey was really getting out of the matter was mainly from Vadderung in exchange for just being available for Harry to 'hire'. It was probably only a dollar because some aspect of the job appealed to him and he just has to keep up his code of being a mercenary so he has to charge something.
Like, Kincaid would probably not care much about money either if someone was shopping around contracts on Nicodemus. Payment would just be a mercenary excuse for doing something he really wants to anyway. (Actually, with Nic left on the run at the end of SG and Marcone having put a price on him, I wonder if Kincaid will be tempted to leave Ivy's service now that she's older and go head-hunting)
Disagree about Kincaid. He has a lot of expenses to pay for every job. That equipment doesn't come cheap.
He also seems to have developed a certain degree of fondness for Ivy. Unsure if paternal, fraternal, or just a friend, but we see a dose of it in Small Favor. I think he's sticking with her for the long haul.
