Breakfast in Milan, like in all Italy, means usually a cappuccino and a croissant (which the Milanese call "brioche" while in other parts of Italy they might call them "cornetto" or with other names). All bars will serve you this at a price which will vary from 2.50 to 3.5 euros. Most Milanese people will have their breakfast standing at the bar, however in most bars you can also sit down at one of the few tables. Then if you want to treat yourself you might pay even up to 10 euros in the most famous "pasticcerias", which are cake shops where you can also sit down and have a coffee or a cappuccino with a slice of cake or a croissant. There are a number of nice "pasticcerias" in Milano, among them:

Sant' Ambroeus - Corso Matteotti 7: it's one of the most famous, and most expensive pasticcerias of Milano.

Cova - Via Montenapoleone 8: very stylish it's where the rich ladies who live in the centre of Milano go to have their breakfasts, it's very expensive since it's in the street where all the richest shops of Milano are

Marchesi - Via S. Maria alla Porta11/a: very nice and makes famous Panettone and Cakes.

Gattullo - Piazzale di Porta Lodovica 2 - Milano - Tel. 02.5831.0497
Website: with pictures
This is a bar and pasticceria. Very old-school and very well-known in Milan. Famous for its cakes and petit-fours (sold in elaborate boxes, nice gifts). TIP: The Porta Lodovica  taxi stand is 10 meters away, always easy to get a cab.