4. Mat Ryan

Club Brugge to Valencia, $9.7million

The current Socceroos number one moved to Spanish giants Valencia from Belgian Cup winners Club Brugge in 2015 on a six-year deal as a 23-year-old. Ryan had just won the Belgian Pro League Goalkeeper of the Year award in back-to-back seasons prompting the interest.

Ryan’s time at Los Che hasn’t quite worked out as hoped since his switch, never establishing himself as the side’s first choice stopper. He’s made 23 appearances in two seasons in Spain but was loaned out to Genk in Belgium last season and has been heavily linked with Brighton & Hove Albion more recently.

3. Mark Bresciano

Empoli to Parma, $9.8million

Back in 2002, Bresciano made a big-money move as a 22-year-old to Parma, who at the time were a huge club, having won the UEFA Cup in 1995 and 1999, along with the Coppa Italia in 1992, 1999 and 2002.

Bresciano admitted as much upon the move from lowly Empoli, stating "the structure of the club, the facilities, its popularity means you are under a lot more pressure to get a result”. The midfielder did well at the Crociati, spending four years there in Italy’s top flight and making almost 150 appearances before joining Palermo in 2006 where he enjoyed another four Serie A seasons.