#4. Cristiano Ronaldo - Manchester United to Real Madrid for £80m (2009)

In hindsight, Cristiano Ronaldo’s £80m transfer to Real Madrid looks like daylight robbery.
The Portuguese spent nine seasons at the club and scored an unbelievable 450 goals in 438 games. This made him the club’s all-time leading goalscorer in all competitions and in the league by a huge margin.
Ronaldo played a crucial role in winning 15 trophies during his time with Real Madrid including four Champions League titles of which the last three were in succession.
In addition to winning all the team accolades, Ronaldo notably won four Ballon d’Or awards and three European Golden Boots among numerous other individual honours. He also has a plethora of records to his name as well.
Interestingly, when Ronaldo left Real Madrid aged 33, it cost Juventus £88.5 which is more than what Real Madrid paid for him when he was 24.