Ask for discount from property manager?

[Adam Craig]

I have been with my property manager from the start, about 5 years now. Its one of the larger companies in my area. I now have 21 single family homes being managed by them. All in all I am happy with the job they do and would never consider self managing. 

Fees are pretty standard. New leases they take entire first months rent. Then 10% of gross monthly rents. $200 lease renewal fee.

Is 21 properties and counting enough to negotiate some of the above fees? I get volume pricing from most of my workers because I keep them so busy, is property management the same?