Do you do toilet training?
I do, and I do enjoy scat as a type of humiliation training -- but there is a SUBSTANTIAL additional fee for "full-toilet," that is, scatological play, that makes it hard to afford for all but the most dedicated players. This is because of clean up and safety risks. I also only do this with clients who I already know very well, this will NOT be a first-session type of thing. To prepare for a full toilet session, I require two days notice, to regulate my internal cycle so that I can "perform" adequately.
I charge about $500 for a one hour scat session.