As many here know, I bake a lot during the holidays and buy some dry supplies in bulk, but not the kind of bulk you're describing, Hols.
I buy 25 lb sacks of bread flour and all purpose flour and store it in galvanized cans, and make sure I've always got at least 20 lbs of sugar on hand.
Storing huge amounts of bulk dried goods and keeping them properly rotated so they stay fresh can be a challenge. It's also tough to ensure they remain dry, bug-free and rodent free.
@Alligatorob, I've seen that list before. DH & I have a far deeper pantry than most, but nowhere near the 800 lbs of grains and 120 lbs of legumes that they recommend for 2 people. (Not to mention 16 lbs of salt, 5 gallons of cooking oil, and 120 lbs of honey.)