If you seriously want to try to figure out his payrate, you'd probably need to analyze his post history. What days of the week and hours of the day he typically posts during would give you a timezone approximation. Some careful reading would help narrow down the group paying him by determining narrative vectors.

I recall seeing a payrate guide for shilling on 4/pol/ (which is a terrible read now) recently, I think it was specifically for the ADL or JIDF. Point being, it shouldn't be impossible for the payrates of other organizations to be floating around out there.

Don't discount the value of ideological pawns, though; some shills really do it for free - which should technically make them trolls.