You can order directly from Gold Medal Models' website (www.goldmm.com)
Be advised that the photetch set for the Arizona costs more than the kit, but it's worth every penny. I'm building the Trumpeter Arizona myself right now and the March FSM article is indeed a valuable reference. You may also want to check out the December 2001 FSM issue, which reviews both the kit and the PE brass set. Good luck and have fun!
Paul
"A man's GOT to know his limitations."