There is a difference between stockpiling and hoarding. Especially when it comes to food items with a limited shelf life.
Sometimes there's a fine line and sometimes it's pretty obvious. And it differs for everyone based on their needs.
You can add another column to your Price List and write down how much of that item your family uses in a month and go from there.
You may think buying 25 boxes of mac & cheese is ridiculous if your family only uses one box a month. If my kids eat it 4 or more times a week, that'll only last 6 weeks. (Am I being a little transaparent here? hehe...)