My first stop is usually the index in my local yellow pages. In this case, nothing under "Threaded Rod" but "Fasteners, Industrial" led me to several possibilities, including one that lists "TH ROD" in a liner ad. ( And hey, there's "Farm Equipment" on the same page! /w3tcompact/icons/grin.gif )
Remember, HD, Orchard Supply, Lowes, etc. are "Home Improvement" stores, not "hardware" stores. As a matter of fact, of all the competing chains locally, only 3 branches of two of the chains bothered to list themselves under "hardware" in the yellow pages.