Nrchy,
McMaster Carr has threaded brass rods at 69-72" lengths 5/8 inch right or left hand thread. They are $58.19 each. 5/8" right or left hand thread brass hex nuts at about $4.00 and change each. For a two shelf rack, you are looking at about 320.00 for the rods, washers, and nuts in brass. I've been building different style DIY racks myself (currently have 3 configurations complete), and a two shelf model with large solid rock maple slab shelves and 5/8" brass hardware prices out at around 440.00 for materials.