You can get them locally from Calsak Plastics off of Old Norcross Rd. on Sweetwater Rd (east of I-85).
1/2" rod for $0.66/ft (6-ft rods) and 1" rod for $2.10/ft. They have 1/2", 7/8", and 1" in stock and can get other diameters as special orders. They also have sheet acrylic in various thicknesses.
(This was from a recent email from MrEd, who had to get rods locally recently.)