Costco. They sell KAF. Also, rumor is that Central Milling is the manufacturer for the organic Kirkland signature AP flour.

I buy my flour at Costco, but it's King Arthur. I didn't know Costco had organic.

The bread flour is in a 10 lb bag, which OP could easily go through at a loaf a week. But buying a smaller quantity elsewhere so they can get organic won't break the bank for such a small batch.

I have been milling my own flour since 2005.

Wait, people mill their own flour? Where have I been? Off to google….