Pure Iron (or ARMCO iron) source (rod or bar) needed (USA)

I'm looking for a few feet of at least 99.5% pure iron rod or bar, any size
from at least 1/4" square or round, but not over 1/2" thick. I need it for
element collectors looking for pure samples of various metals. Must be
reasonably priced (not that sky-high Goodfellow stuff) and available to
anyone in small quantity (not just companies). Any old surplus ARMCO 99.8%
pure iron would be fine.