Go to the dollar store and look at the food there. Everything has sugar in it.(It's also not a great deal due to portion size, but if you don't have much money it's an easy way to get variety). The cheaper the food, the more likely there are cheap sugars meant to made it more palatable

Or look at restaurant/fast food-- the healthier options are the 'premium' options. But if you've got a few buck and want to feed a whole family, a bunch of burgers is still reasonably priced for someone low income