Do you have a local homebrewing club? We have a very active community in my city, and they frequently do "Bulk Buys" of various ingredients and equipment direct from the manufacturers, or wholesalers. Just last weekend, they received over $14,000 worth of grains and had a big party Friday night where they split up everybody's order. I got 250 pounds of grains for around $180, but that included a lot of specialty grain. As an example, I got a 55 lb bag of 2 row for around $25 CDN.
Find your local grain wholesaler (ask a microbrewery), contact them, and see how big of an order you'd have to place before they'd deal with you. Then gather up some other homebrewers and put in a bulk order.