The standard fee is whatever they can get away with charging you, and is also relative to the amount of management business they have.
If you need them worse than they need you, it's their game.
But really, $100 is very reasonable for a renewal if the agent is doing a good job and you have tenant turnover. If you have one tenant in the property for 15 years, well that's not such a good deal for you.
Your job is to guess which it will be!
For a first time rental anywhere from 1/2 to a full months rent is the norm.
--76.87.xx.xx