The prebate is there to keep politicians from exempting food from the tax. The idea is to keep the tax pure with no exemptions. I believe, however, that in order for it to pass at least 3 exemptions would have to be added; exemptions for: primary residence, medical expenses and religions.
A new car is actually quite doable. With about 25% more takehome pay (i.e. FICA, medicare & income taxes) a person making $50,000 should be able to save the tax amount on a new car in less than a year. However, a new house with say $35,000 tax paid up front would simply be out of the question for the average person.
An exemption for medical expenses is a no-brainer, since nobody wants the government to profit from somebody’s misfortune.
And, the religious exemption is a requirement to keep a clean separation between church and state.
That leaves the employer with about 9% to reduce his prices -- if he choses to do so. Add the Fair tax, and prices rise 18% for domestic goods. 30% for imports.
Assuming your purchases are 50-50, that is a 24% average price increase.
The exemptions you list make sense, and they may be necessary to get the votes to pass this abortion. But the rate can't stay at 23%. Health care alone represents 16% of GDP.