A few things a like that. I get 1L bottles of a tomato pasta sauce I like. It costs about US $2. It tastes good and has a custom bottle for the brand. How do they do it? I couldn't grow the ingredients from seed for that price as the seeds alone would exceed that cost. Then making the sauce, the bottle, then shipping.
but the point still stands - sure the seeds might've only cost you a few cents (or even, free if you know a nice farmer who'll give you some). But think about the time it takes to grow, and the amount of effort required to grow enough to make one jar of tomato sauce...