Ahoy Storm ,,, the last Silicon Bronze plate stock , that I purchased was from Alaskan Copper and Brass :
http://www.alascop.com/pdf/brbr/silicon_comm_sheet.pdf ,,,,,, they shipped that small order to me on Langkawi Island , Malaysia . The shipping cost just about the same as the metal , itself .
Since there is such a heavy presents of US Military in Hawaii ,,, you might even find some silicon bronze supply, there .