For example, Roy Keane for £3.75million in 1993, Cristiano Ronaldo for around £12million in 2003 and Wayne Rooney for less than £30m a year later were all unquestionably excellent buys.
However, United have had their fair share of flops too.
Former Arsenal superstar Alexis Sanchez - who arrived as part of a swap deal that saw Henrikh Mkhitaryan moved to the Emirates Stadium - arguably belongs in that category.
Sanchez moved to Old Trafford in January 2018 after scoring 60 Premier League goals in 122 Premier League appearances for rivals Arsenal.
Alexis Sanchez pictured (left, leaning forwards) lining up for a team photo ahead of a UEFA Champions League game between Manchester United and Valencia in March 2018
However, the Chilean only netted three times in 32 league games for United before departing for Inter Milan in August 2019.
Sanchez was paid a basic wage of £350,000 a week by United, plus image rights and bonuses.
Despite earning significantly more at United than he had at Arsenal, Sanchez has previously said that he wanted to return to the Gunners after just one training session in Manchester.
He blamed a lack of unity within the United squad under then-manager Jose Mourinho and said that he was not impressed by 'what was happening inside the club'.
Sanchez - who had been linked with a move to United's nearest rivals shortly before he arrived at Old Trafford - told all in a video posted on Instagram in 2020.
In the video, Sanchez explained: 'Before, I had an agreement with Man City, but due to football issues, I accepted the opportunity to go to United. It felt tempting and it was something good for me. I liked this club a lot when I was a kid.
'Eventually, I signed but I didn't ask for information on what was happening inside the club.
'Sometimes there are things that you don't realise until you get there and I remember the first training session I had, I realised a lot of things.
'After the session I got home and I told my family and my agent: "Can you not rip up the contract to go back to Arsenal?" They laughed, I told them there's something that doesn't sit right, it doesn't seem good.
'But I already signed, I was already there. After the first few months I carried on having the same feeling, we weren't united as a team in that moment.'
Sanchez won the FA Cup twice with Arsenal, having previously lifted six pieces of silverware with Barcelona.
He did not win any trophies with United but has since won five titles with Inter, including Serie A on two occasions.
Sanchez joined Udinese last month when he signed a two-year contract that will expire six months after his 37th birthday.