DO NOT BUY $100+ rods...that is idiotic.
Go to Ace Hardware. Somewhere very close to the aisle full of assorted nuts, bolts, screws, washers, etc...there will be a section of long red packages from K&S Precision Metals. They make solid brass rods and hollow aluminum tubes in 12" lengths in a variety of diameters that will match up to any caliber you need. They cost $7-$10 each.
I use these rods for suppressor alignment, and more frequently to align my Magnetospeed chronograph.