1. Dimitar Berbatov - £30.75m - September 2008
Manchester United spent the summer of 2008 pursuing Tottenham striker Dimitar Berbatov, but it was just a dramatic few minutes before the close of the transfer window that they got their man. And the Bulgarian didn't come cheap at £30.75m - United's most expensive ever signing.
Compared with Eric Cantona upon his arrival, Berbatov has fallen well short of expectations. 48 league goals in 108 appearances is not a bad return, but that he didn't even make the bench for the 2011 Champions League final against Barcelona spoke volumes. Will likely be best remembered for his saved penalty against Everton in the semi-final of the 2009 FA Cup in which his casual spot-kick made him look like a plonker.
2. Rio Ferdinand - £29.3m - July 2002
When United paid Leeds United £29.3m back in 2002, it appeared a crazy amount of money to spend on a defender. Yet Rio Ferdinand has been a linchpin of the squad in the intervening decade (excluding the eight months he was banned for missing a drugs test) and was worth every penny.
United won the league in his first season and another four after that. He also helped United win the Champions League in 2008.
3. Juan Sebastián Verón - £28.1m - July 2001
The arrival of Juan Sebastián Verón from Lazio was one of the most glamourous signings in the history of the Premier League - yet sadly for United it was only that, with little substance to the £28.1m man.
The Argentine never settled at Old Trafford and made just 51 league appearances in which he scored seven goals. Two years after arriving, he was sold to Chelsea (who incredibly paid £15m for a player who would make just 14 appearances for the west Londoners).
4. Wayne Rooney - £27m - August 2004
After bursting onto the scene at Goodison Park, and then appearing as though he could carry England to the Euro 2004 title before injury struck, it was obvious Everton would not be able to hold on to their boy wonder.
And it was Manchester United who came calling, splashing out £27m on the then 18-year-old. It was a huge fee for such a young player - but in retrospect a bargain. On his debut he scored a Champions League hat-trick against Fenerbahce and he never looked back. Rooney is currently the fourth highest scorer in Manchester United's history.
5. Anderson - £20.4m - July 2007
Still only 24-years-old, there remains a little more time for Anderson to justify why United paid Porto in excess of £20m for the midfielder's services.
Yet it must be said that the box-to-box midfielder has been disappointing in the five-years he's spent at Old Trafford, showing only marginal progress during that period. Although, if Anderson does nothing else, he will be able to say he scored United's sixth attempt from the penalty spot in the 2008 Champions League final against Chelsea. John Terry missed with the next spot-kick as United claimed their third European Cup triumph.
6. Ruud van Nistelrooy - £19m - June 2001
Alex Ferguson pursued Ruud van Nistelrooy for years, and it was only injuries that stopped the Dutch striker transferring from PSV Eindhoven to United earlier. He would be worth the wait.
In 150 league appearances he would score 95 goals, while his record in the Champions League was incredible. During his time at United he scored 38 Champions League goals - more than any other United player in the club's history. After five-years at the club he was sold to Real Madrid.
7. David de Gea - £18.9m - June 2011
United needed to replace the retiring Edwin van der Sar with a top-class stopper, yet while David de Gea clearly had ability, Ferguson's decision to put his faith in a 20-year-old with relatively little experience surprised many.
Signed from Atlético Madrid only last summer, the jury remains out on the Spaniard. He started last season shakily but finished it well.
8. Michael Carrick - £18.6m - July 2006
Another player Tottenham reluctantly sold to United, Michael Carrick has been a consistent force in Ferguson's midfield since joining in 2006.
Among other honours, the England international has four league titles to his name and a Champions League medal. There are few better passers in the Premier League, but his inability to find the back of the net remains a frustration.
9. Nani - £17.3m - July 2007
Unfairly compared to his countryman Cristiano Ronaldo after arriving from Sporting Lisbon in 2007, Nani had a slow start to his Old Trafford career.
Yet he has begun to break free of those shackles, netting 10 goals from midfield in each of the last two seasons, as well as completing 10 assists in the league last term.
10. Owen Hargreaves - £17m - July 2007
Consistent displays at the heart of Bayern Munich's midfield, and then impressive performances in an England shirt under Sven Goran-Eriksson brought Owen Hargreaves to the attention of the British public, and Alex Ferguson, and in the summer of 2007 he joined Manchester United in a £17m deal.
Some described him as one of the most naturally talented midfielders England had ever seen - yet Manchester United fans didn't get much of a chance to see for themselves. Injuries would limit Hargreaves to just 39 appearances for the club before he was released last summer.
11. Robin van Persie - £24m - August 2012
Robin van Persie, Ferguson's most recent and final big-name signing, has scored 25 league goals in his first season at the club as United reclaimed the title from Manchester City with ease. He is currently the Premier League's top scorer after an excellent debut season at Old Trafford. The Dutch striker missed out on the PFA Player of the Year award recently but arguably should have won the accolade ahead of Gareth Bale who will end the season without any silverware. Van Persie fittingly secured the Red Devils’ 20th league title with a hat-trick against Aston Villa.