Appropriate sales commission on $3 million multi family block ?

[Peter Fro]

What commission is typical / appropriate on a multi family block with a sale price of $ 3 million?   This is in respect of an unsolicited bid received by the broker from a single party.  There is no extensive marketing campaign or advertising needed:  broker I bought through a couple of years ago has approached me to sell to an interested buyer she has identified and she is proposing 6%.    I have the feeling this is on the high side for multi family transaction of this magnitude.    Any thoughts?