10 most expensive transfers between La Liga clubs

7) Asier Illarramendi: Real Sociedad to Real Madrid – £27.2m

Asier Illarramendi failed to live up to expectations at Real Madrid after they spent big on him

Yet another product of Real Sociedad’s youth system, Illaramendi came into prominence in 2012 and 2013 for the Txuriurdin. Plying his trade in central midfield, he was dubbed the next Xavi Alonso and even won the La Liga Best Midfielder award in 2012/13 at the age of 23.

It wasn’t long before Real Madrid spent €32.2m to bring him to the Bernabeu – a move that people believed showed that Real Madrid were moving away from the Galacticos policy of buying proven stars. It also made him Real Madrid’s most expensive Spanish player.

However, he never really established himself in Madrid and made the move back to Sociedad after just two seasons for a cut-price £12.5m – less than half his original transfer fee.