I Had It Easy
You know, I think I got off easy when I first started doing listing and buyer presentations.  You see, I worked in Connecticut and on the Connecticut forms, there was a clause that read:

"Please note that real estate commissions are not fixed or set by law and may be negotiable between you and your broker."

The Opening to the Ultimate Closing
Yeah, I loved that clause.  Because while other agents out there glossed over it and tried to get the buyers and sellers to look in the other direction when they went through those terms, I addressed them head on.  In fact, that's why I so clearly remember exactly what the wording of the clause was - I used to read it out loud each time.  The key wasn't in the reading of them, it was in the words I used that immediately followed which were:

"Abosolutely true - you're welcome to pay me more, but I don't work for less."

And I'm Worth Every Penny
It was rare that after hearing that someone would address the issue of cutting my commission.  But on tht very rare occasion, they would say something like - are you sure you won't work for less than x%?  And my response would always be, "nope - and I'm worth every penny."  And most people were happy with that.  Why?  Because I had established that value of what I had to offer up front and I was solid in my conviction as I stated my price.  In short, I believed it.  I believed that I was worth every penny to them.

Price Isn't the Issue
Price is rarely the issue - it's usually a question of value.  You see the problem isn't with whether or not you're worth what the client is paying, it's in whether or not they see the value in what you're offering.  If you offer a free pre-closing hose cleaning to someone who owns a cleaning company, they aren't going to see the value.  If you tell someone who is completely convinced that they are OK about their move and not stressed at all that you give emotional and moral support to help them emotionally weather the storm of their home sale - they won't see the value.  But if you tell the a mother of five that you'll provide a free pre-closing house cleaning - she'll kiss your feet.  And the first time buyers who are terrified that everything will go horribly wrong are just dying to hear that you're going to hold their hand.

The Moral of the Story? 
Make sure that they know what they are getting for their cash and that they value those items.  Then be clear that you also value your services.  If those two pieces come together, you'll get your price - guaranteed.