I don't see what state you are in, but if you are in an agricultural state, there may be feed mills near you that make their own feed, much cheaper than the large brand names. I have been buying an all-flock feed, 20% protein, for 9.99 for 40lbs. It is made about 30 miles from my home, and sold locally. So you might check around to see if anything is available. Of course, if you live in a very urban area, maybe not much chance of that.
Are you planning to do the processing yourself? I think there are some good threads to follow on that here on this forum. Might as well start eating those pigs with feathers!