6. Christian Vieri - £32m | Lazio to Inter Milan in 1999
The Zlatan Ibrahimovich of yesteryear, Vieri was renowned for switching clubs for mega-money.
Inter joined the long list of suitors, spending a record £32 million to bring the Italian to the San Siro.
Money well spent? Well, Inter only lifted the Italian Cup in 2005, and they struggled to challenge for the Serie A title during Vieri's spell with the club.