3) Ronny Johnsen – £1.2m
A solid defender involved in United’s treble winning season of 1999, Ronny Johnsen was quite a find at only £1.2m.
4) Cristiano Ronaldo – £12.24m
One of United’s best players of recent times, Cristiano Ronaldo only cost just over £12m when he joined as a little-known teenager in 2003, and he went on to cost £80m when he left for Real Madrid in 2009.