I've called Kelly Realtor several times.  They have a company that does property management but I've been unable to get a return call.  Maybe they have plenty of business, but usually salespeople consider the phone ringing to have the smell of $$.  If they called me back, I'd be inclined to not use them simply for the lack of response after 3 voicemails i've left.

Anyone have any suggestions for the Waco area of a good property manager?

In general, what should I expect to pay per month?  I've heard 8-12% and usually half the first month's rent, but know it probably changes quite a bit depending on part of the country you're in.