For cheap produce any frugal gourmand should check out the Haymarket. Located right by Fanueil Hall (you can take the orange or green-line "Haymarket" stop) , Haymarket offers a wide variety of produce at discounted prices. There are no fancy stalls or set-ups and it's always busy and sometimes quite noisy. Our friend Bob likes to swing by after work during the summer to buy fresh strawberries for his home-made daiquiris and margaritas! Towards the day's end you'll see squashed veggies and fruit on the ground (the city has even installed bronze 3-D art on the streets and sidewalk to replicate this) and you can even haggle for prices right before close. If you're in the area, or need to feed a large party, this is definitely a good place to shop at.