For starters, the consensus to my knowledge of economic analysts is that the average small business spends $700 in compliance costs for every $100 of federal income tax paid(Tax Foundation says $724 per $100: http://www.fairtax.org/pdfs/small%20businesses.pdf
Direct enforcement costs saved would be over 90%, and with direct compliance costs would total several hundred billion dollars per year. Compliance costs alone were estimated ten years ago as between $225 and $300 billion per year.
http://www.fairtax.org/pdfs/currentsystem.pdf
As you can see, pretty soon we're talking about real money.:>)