Like Runner, I live near St. Louis and the only local source I am aware of is in Fenton.
My son lives in central MO, so I swing by Grafs to pick up a coupla pounds of powder, as needed, when visiting him.
Grafs will ship as little as three pounds of powder to any U.S. location, so they are a good source for anyone who is limited by the amount of powder they can possess, or who doesn't want a large supply of powder in the house.
J.D.