If you're a consumer (rather than a professional) and want to save money on shipping, you can order in advance and buy a 5 pound bag of Giusto's High Performer High Gluten Unbleached Bread Flour for $5.40 at Earthbeam Natural Foods, 1399 Broadway, Burlingame, CA, for $5.40.
Note that Earthbeam does not regularly stock this item, so you will need to call the store in advance at (650) 347-2058 and ask them to order it for you. You'll also need to specify Order Number 102006. Earthbeam would love your business!
This is for walk-in only...this is a very small retail store and they don't do mail-order. For Giusto's mail order, you can access http://www.worldpantry.com/cgi-bin/ncommerce3/CategoryDisplay?cgmenbr=132201&cgrfnbr=171236
Hope this helps. And no, I don't have anything to do with Earthbeam but they went out of their way to be helpful.