I live in the Ohio Valley and found the best place to get flour in bulk is Thompson & Sons Bakery Supplies in Dillonvale, Ohio. I've been driving by it all the time to go to the high school for one thing or the other for my three teenagers (doctors appointments and such) and wondered if they sell to the public, which they do. I went over there today and got a price list and a bag of A.P. flour for $17.50 (50#). They also carry organic flour, whole wheat, the works and any other kind of baking products you might need along wth cheese and some deli meats at unheard of prices (CHEAP!!) per pound per tube. Still worth the drive. They have trucks that deliver, but not sure how that works and the minimum order required for that and charges associated. They have a small website (very hard to find), but it doesn't list prices. You'd probably have to have them send you one or pick up one.
Thompson & Sons Bakery Supplies
P.O. Box 606
52 Second St.
Dillonvale, OH 43917
FAX(740) 769 -2804
Let me say I am very pleased with the flour I got and found two five gallon buckets with seal tight lids at the hardware that store it all quite nicely.