And King Arthur all-purpose flour has 11.7% protein...
Central Milling Organic Bakers Craft is a blend of hard red wheat, malted with 11.5% protein. The Costco item number is 475605 if your store doesn't have it -- I requested it and my store is carrying it now. I just saw it 2 days ago in the store at $14 for 25 lbs, which comes out to $2.80 for 5 lbs. KA at Walmart is $4.22. Plus, this is unbleached organic so no GMOs.
Then go to the bakery section of your grocery store, ask if they have buckets - the cake icing comes in them, make nice and they'll give it to you for free. Then get a screw top "gamma" lid from Home Depot for about $6. All that = big ol' bucket of flour storage.