The Kaufingerstraße pedestrian zone between Marienplatz and Karlsplatz often has many fruit stands. They typically have affordable and seasonal produce. Interestingly the prices can vary substantially. I tend to be cautious if there is an 'angebot' (sale), because occasionally the fruit is moldy. It also appears many will display their more picturesque fruits along with a sign stating no self service.
That being said once you find a good one to frequent the sales people are more friendly and just maybe you'll receive some of the nicer produce that they mysteriously pull from behind the table.