Any food will make you sick. You can find crap food at any store. Dollar stores don't have the monopoly on that. I think that 90% of "food" at ANY store is crap.
Food is extremely inexpensive if you learn how to make stuff yourself and don't buy anything that is prepackaged. Don't buy Thousand Island dressing for example, make it from base ingredients. Instead of paying $3 at a regular grocery store, you can make it for 25 cents, if that. Croutons? Costs $2.50 at the store, or make them at home in your oven for 10 cents or whatever. All you need is bread and spices, and as I said, this is not a $2.40 savings, oh no. it is a 2,500% return on your money.