The problem with Chanel is that you NEVER know if they have your bag in stock. You are so excited, creditcard on hand, ready to get your favorite Chanel bag that you've long waited for. Then you go to London/Paris/Rome or any City just to get your bag. Some will travel as far as US or from HK. Then you visit the Chanel boutique and the SA tell you that your bag is out-of-stock and need to wait until Monthday and we HOPE we will have your bag in stock by the time. Well, you need to travel back to your country on Sunday. BUMPER! This has happened to me though in Paris. You don't want that to happen to you. So what's the best place to buy a Chanel bag:
1). Forget about the tax-refund. There's no price for getting the bag you love and the extra tax-refund is a bonus. London has 10 times more boutique than Italy. I would look for the bag in London first and if I found any, I buy immediately.
2). You might be able to get more tax-refund in Italy, I know it's 12%. But if you are lucky enough to get in Italy and they have your bag, then buy it.