If you go to Milan in the beginning of July almost all clothing stores has mayor sales on their spring and summer collections. I got some clothes at 60% off! Otherwise can Milan be quite expensive but I think they have a big sale in January as well.
What to buy: Clothes!
What to pay: You'll probably ending up spending too much like me ;)
A great location for everyday shopping is the Corso Buenos Aires. A wide, busy street, it's everything you need from a high street - clothes, shoes, accessories, department stores, cafes, DVD and music shops etc...
Beauty of C. Buenos Aires is that mixed in with the everyday are shops that sell those 'labels' - and chances are that you may get them a little cheaper than in the Fashion District itself.
What to buy: Lots on offer
What to pay: Wide range
Most shops... I found clothes to be more than twice as expensive as compared to the US. Branded clother such as Ralf Lauren, Hugo, Ck, Tommy etc where another third more expensive.
Also the sizes are european sizes so they are a shade smaller.
I found Italians to be very brand concious and almost every one like to wear a brand and flash brand names.... I did found many small shops that were selling branded clothes however some of them seem to be questionable as to if they were real authentic... seemed fake.
Buy something if you want to remember the trip.. however if you are a serious shopper then boost you credit limit / bank balance before you stroll into italian malls
What to buy: Mostly trinkets for friends & family...
What to pay: You will always over pay.. there are no deals in Milan.. sorry I was there for only a day and did not find any and maybe if I stayed longer I may have found something.
Galleria Vittorio Emanuele II is a historic cross-shaped shopping mall which has a lot to offer. Stroll around and enjoy.
OK I can't afford Gucci, Prada and the rest of them but I bought a lovely pair of pants from a street trader and when people ask where I got them I can just say "Milan Dahhling"