Grocery salad bars aren't the best or cheapest options for fresh produce, but if you're shopping or cooking for one, they can be a windfall. Stop by and grab just the ingredients you need for soups or other dishes, with no fear of overbuying, no leftovers and little pre-cooking prep needed. Image from stevendepolo.
While this probably isn't cheaper than buying bulk groceries to make soup (since you have to pay by weight at the salad bar, and raw ingredients may be cheaper depending on how much you buy,) it does allow you to better control the ingredients you get.
For example, you could grab several different kinds of beans, fresh spinach, sliced onions and tomatoes for a simple, tasty soup you can just throw together when you get home, enough for just that night, or that night and lunch at the office tomorrow. Plus, there are plenty of toppings, like shredded or crumbled cheese or croutons. You end up with just enough ingredients for one or two meals without mountains of leftovers hanging around your kitchen or half empty bags and cans of ingredients you have to use up or toss.
10 Things to Buy at the Salad Bar for Your Soup [The Kitchn]