Berlusconi says the transfer is proof that Milan can still shop at the top table.
"This transfer has demonstrated that Milan can still invest substantial amounts in top players," Barbara Berlusconi, the daughter of owner Silvio, told the club's website.
"Our club has, in the last year or so, completely re-organised costing and investments.
"It was about rationalisation, and various sacrifices were needed, not just in terms of player salaries but also about re-positioning the brand.
"Milan were the first club to choose to organise their accounts and balance the books.
"Thanks to this strong decision, we can only stand to benefit with our stars of the future, and still also be able to make some important acquisitions."