The problem is the 20-30% figure is fictious. If you take all consumption and include all federal taxes, you are at about 15%. And if you only count the taxes paid by businesses, you are only at about 7%
The increased costs are real enough as you could see with a bit of research on the FairTax website.
You don't seem to grasp what the increase stems from. Check the FairTax derivations of the increase.