The National Sales Tax
Fun fact: the national sales tax is an idea originated by the Church of Scientology. Bruce Bartlett explains:
For those who never heard about it, the FairTax is a national retail sales tax that would replace the entire current federal tax system. It was originally devised by the Church of Scientology in the early 1990s as a way to get rid of the Internal Revenue Service, with which the church was then at war (at the time the IRS refused to recognize it as a legitimate religion). The Scientologists' idea was that since almost all states have sales taxes, replacing federal taxes with the same sort of tax would allow them to collect the federal government's revenue and thereby get rid of their hated enemy, the IRS.
L. Ron Hubbard and the Church of Scientology didn't pitch a national sales tax because it was a good idea. They just hated the IRS. That might have something to do with Hubbard embezzling millions.
A national sales tax has been pitched in Freedom Magazine. The publication is run by (you guessed it) the Church of Scientology.
Find an economic idea conservatives love and it is bound to have a bizarre origin.