Sorry but a fellow in the 5th New Hampshire (my old group) then doing Confederate, heard the late George Gorman inspire the term way back at a reenctment in the 1960s.
http://wesclark.com/jw/forigin.html
"...Gorman had a business of selling Civil War artifacts in Philadelphia, and was known for wild behavior. The Maryland State Police led Gorman away from the 1962 Antietam event for some behavior they didn't agree with, but he reappeared in time for the 1963 Gettysburg event, and there exists a photograph of Gorman meeting then Governor George Wallace. (Here's another.) According to the Centennials the early years of reenacting were fraught with passion from the Civil Rights activities then going on, and units and events were described to me as often being quite "rednecky." (What a surprise.) But Gorman gets the credit for popularizing the term "farb." (Kimmel remembers that he turned the adjective "farby" into the noun, "farb."
According to the Centennials with whom I have spoken, the story about Gorman rolling his eyes heavenward and piously declaring, "Far be it from me to criticize unauthentic uniforming" is not how the term farby got started, and Kimmel, especially, would like to debunk it once and for all. While Gorman may have said this, it wasn't how the word was created. Many other accounts of the creation of the term farb are in circulation, but the most credible and agreed-upon is the Gerry Rolph/Blackhats account I relate here....."
"Etymology
The origin of the word farb (and the derivative adjective farby) is unknown, though it appears to date to early centennial reenactments of the American Civil War in 1960 or 1961.[2] Some think that the origin of the word is a truncated version of "Far be it from authentic."[3] An alternative definition is "Far Be it for me to question/criticise,"[4][5] or "Fast And Researchless Buying".[6]Some early reenactors assert the word derives from German Farbe, color, because inauthentic reenactors were over-colorful compared with the dull blues, greys or browns of the real Civil War uniforms that were the principal concern of American reenactors at the time the word was coined.[7][8] Since the word was coined, it has become widespread throughout the reenactor community."