Seller's ask me this questing all the time.  It is really a marketing question.  Right now the market niche for a flat fee mls listing is for sale by owners and industry insiders (commercial brokers, former agents, attorneys, appraisers, mortgage brokers, developers, and the like).

Once people hear about our service many wonder why everyone does not try it.  Believe me I know that it is not for everyone and good traditional real estate brokers will always have a job.  If you want to have your hand held during every aspect of the transaction then a flat fee mls listing is not for you.  If you are willing to put some work into selling your own home in order to save thousands of dollars in commission then this may be a good route.  I believe that a lot more people would try this avenue  if they were aware of it.

Right now I estimate that in the range of 1-2% of the market lists their property through a flat fee mls service like ours. Getting the word out that we exist to all those people that might be interested is a tough marketing problem.

Mass advertising(TV, radio etc.) does not seem to make sense from a ROI perspective.  Good traditional real estate agents get a huge chunk of their business based on referrals.  Many have exceptional people skills and personal relationships can seal the deal for these brokers.   Additionally it is hard to get the general public to see through some of the FUD (fear, uncertainty, doubt) pitch that some full service brokers throw at them.

So any way where am I going with all of this?  In my mind the only reason more sellers don't explore the flat fee mls option is that they either unaware it exists, don't fee comfortable doing some of the work themselves or have been given a false impression of what this program has to offer.