Wow! 50# of popcorn? Catholic Samurai, you REALLY like popcorn. We enjoy popcorn, too, and have stocked up a little.
We buy organic NonGMO popcorn and organic cornmeal from the bulk bins at our store. I remember a thread on organic and nonGMO foods that got a lot of responses about the expense of these foods, so for those who know about the worries of GMO foods, check out the prices at your store for organic grains in the bulk bins. I call them "bulk" but you bag it yourself and can buy as little or as much as you want so we buy a little bit here and there and store things in jars or containers that hopefully will keep bugs out. Sometimes the bulk bins don't hold more than a few pounds of something so if you want to really stock up, I guess you'll still want to buy some things in big bags to save money in the long run. We do it this way because it's easier on the budget to try to get ahead a little bit on the foods we eat anyway and then just keep rotating. The budget doesn't always keep up as we keep eating!
I have a tip for you if you are planning on stocking up on toothpaste. We added a few of the less expensive items onto our regular shopping trip this week, but the budget didn't allow as much as we had hoped, so instead of toothpaste, we bought a few of the small boxes of baking soda. Baking soda has many uses and is very cheap.