Can you please create a list of 5 ordinary and cheap items that you should stockpile now because of how useful they'll be in the event of a future supply shortage? Make sure that each item has a short description for it explaining the reason or reasons why; between 1-3 sentences should be sufficient. The audience is homesteaders, survivalists, and people who are generally looking to become more resourceful or prepare for tough times. 

Let's include these items for the five: Cleaning Supplies, Peanut Butter, Pet Food, Water Purification Tablets, and Can Openers. There is no need to number each of the items.
Cleaning Supplies - Basic cleaning supplies such as dishwashing soap, glass cleaners, laundry detergent, toilet cleaners, carpet cleaners, and all-purpose cleaners are typically very affordable. In the event of a future supply shortage, these will also be among the first items to disappear off the shelves, so stockpiling any kind of cleaning items now while you still can will be wise. 

Peanut Butter - Peanut butter is a wise item to stockpile (so long as you don't have a peanut allergy) because of the wide variety of meals and dishes it can be included in. Furthermore, peanut butter can provide a good source of protein for those who are on vegetarian diets. 

Pet Food - Do you have any pets, such as dogs or cats? If so, stock up on as much pet food for them now while you still can. People care deeply about their animals, so you can bet that pet food will fly off the shelves fast in the event of a major disruption to the supply chains. 

Water Purification Tablets - Water purification tablets are critical for ensuring that the water you collect is made safe to drink. What's more, you can usually buy hundreds of tablets for super cheap. 

Can Openers - Have you stockpiled any canned food? If so, you'll want to start stockpiling a few can openers as well. 