...and that is 'there's no need to try to control sales'- sales are more stable as a taxable base than taxable income is, according to the research paper at fairtax.org I read.
...and if you think about it, sales taxes already go on in most states- do they hurt the new goods market?  That's an interesting question, one I'd be interested in having more info on.

from the research paper:

"Research revealed that consumption varied less, and was therefore more stable over time than with the current income tax base.  This finding was confirmed using three different statistical measures."

http://www.fairtaxvolunteer.org/smart/stable_gov_rev.html