The whole "Brownbackistan" thing is difficult to trace, having only been added to the Urban Dictionary back in June. The earliest reference to the "pseudo-Christian fascist state where the arts are not publicly funded" seems to be a posting to the Democratic Underground site back in April.
Regardless of the origin of the term, these T-shirts have been selling like hotcakes via the Welcome to Brownbackistan Facebook page, organized and designed by artist Emily Eakes. Because of the state of the arts in Kansas, Eakes has earmarked $2 from every shirt as a donation to arts organizations in the state. There's an interesting wrinkle, however, according to the press release:
"Eakes initially sought partnerships with local arts organizations. She quickly discovered that regardless of their individual opinions, they didn't want to risk offending patrons nor donors. Organizations that will receive the donation dollars will not be released until after the donations are made."