This approach doesn't scale though. Its great that it worked for you, truly, but it unfortunately doesn't scale as a reliable way to budget for groceries
Its too circumstantial to scale to even a dozen people in a locality. It isn't that it doesn't scale to the masses, its that it doesn't really scale at all
It can scale a bit more than one might think. For example, the Wikipedia page for Boston Haymarket even mentions that produce goes to super-cheap near weekly closing.