Can I get a job with you? 
I find it easier to manage to just pay my mods a nominal amount per month. That way they know what they are getting and I know what I am paying for.
Or, you can hand out “bonus” money for a certain number of posts made.
Lots of people will also happily volunteer to mod, most of the aff forums have volunteer mods.
Well, at least now you can put your own banner there and you know what to expect from that spot…