There are also very large transaction costs on both sides of the purchase (explicitly or implicitly) and large organizations with political ties to maintain the cartel for real estate commissions.  

I'm particularly interested in your thoughts on which areas of the contract typically have the most profit margin built in (I believe it to be most upgrades), what margin percentage the companies usually target, how the commission structure is set up, and any stories of what has worked for you. 

Plus, there are usually other fees on top of this since commissions are so low right now.

@Ryan, the closing table is the best place for what I would like to call a "Commission-ectomy".  

Travis,   Sure, there are plenty of "used car salesmen" out there that are trying to talk you into something just so they can get their commission but the good ones really want to help you find what you need.  

Reduced commissions on personal property and investment properties are considered a benefit of the company you affiliate with.  

You might find that going with a realtor who is only focused on their 3% commission doesn't know much about the rental or investment market in their own city.  

The Public Utility Commission of Texas (PUCT) spells out how you can do this.

The state should have a list on the state RE commission website.

She should at least get the listing commission if you're not an agent (assuming she wants it).