Beckham joined Real for £25m six years ago, a small figure in comparison to the fee Real are preparing to pay for Ronaldo.
Most expensive players out of Manchester United:
The fact that he is still playing for England six years on suggests the fee, by comparison, was modest.
Aug 2001: Jaap Stam to Lazio for £16.5m The big Dutchman fell out with Sir Alex Ferguson and so the parting was not unexpected.
Aug 2003: Juan Sebastien Veron to Chelsea for £15m United took a £13m loss on Veron in just two years, but his time at Chelsea was even more unimpressive.
July 2006: Ruud van Nistelrooy to Real Madrid for £11m Like Ronaldo, Van Nistelrooy did not hide his desire to join Real, and made a good impact before age caught up with him.
Dec 2001: Andy Cole to Blackburn for £8m One of the most prolific scorers in Premier League history, Ferguson sold him at probably the right time.
June 2005: Paul Ince to Inter Milan for £7m England midfielder was reluctant to leave Old Trafford, but his experience in Serie A helped him on his path to management.
Aug 2007: Alan Smith to Newcastle for £6m Smith wanted first-team football after struggling with injuries, but his career has stuttered ever since.
July 2007: Kieran Richardson to Sunderland for £5.5m Initially regarded as one of the next generation of bright young things but an inability to hold a first team place saw him move on.
May 2008: Gerard Pique to Barcelona for £5m Came of age following his move to Barcelona. He made just 14 appearances for United, having signed as a kid.
Aug 1995: Andrei Kanchelskis to Everton for £5m Another player to have fallen out with Ferguson, he arrived amid fanfares but despite some famous performances, overall his contribution was minimal.