Marc Overmars
When: 2000
How much: £25m
Nobody can blame Barcelona in springing for the flying Dutchman. His performances in London were some of the finest that the Premier League has ever seen and he helped establish Arsenal as a dominant force in the top flight.
However, despite a strong start in Spain, those old knee and hamstring problems flared up again and diminished his ability considerably, so much so that he was forced to retire in 2004 at the age of 31. He made a short comeback in 2008, though, with Go Ahead Eagles in his homeland.