In the Premier League, Chelsea made some of the best buys of the 2012/13 season in Oscar and Eden Hazard.
Signed from Internacional and Lille respectively, the pair have racked up 151 appearances for the Blues between them. Last season's Europa League win looks like a sign of things to come for the young midfield duo.
Robin van Persie's switch to Manchester United also proved pivotal when he signed for the Old Trafford side in August 2012. Without the Dutchman's 26 goals and 15 assists, it's highly unlikely that United would have won their 20th Premier League crown last season.
Daniel Sturridge's January 2013 move to Anfield has emerged as a phenomenal piece of business. Formerly a journeyman footballer, the striker has finally found a fitting home with Liverpool, where he is currently enjoying his position as the Premier League's top scorer.
For a fee in the region of £12 million, Sturridge was a steal.
At White Hart Lane, Tottenham's acquisition of Jan Vertonghen from Ajax has proved to be shrewd. At £11 million, he was a relatively cheap buy and, when playing in his natural position as a centre-back, he has impressed in his performances for Spurs and the Belgium national team.
In France, PSG were busy buying world-class talents Zlatan Ibrahimovic and Thiago Silva for a combined fee in the region of £55 million, both making the switch from AC Milan. Quite simply, one of the best strikers and one of the best defenders in world football, their move to Parc des Princes was a coup for club and Ligue 1 alike.
In the Bundesliga, Mario Mandzukic's transfer from Wolfsburg to Bayern Munich ended up to be an inspired move. In what must have been a delight for both player and club, the striker netted 15 goals in the league, three in the Champions League and DFB Pokal.
Bayern went on to win all three tournaments and Mandzukic's form saw Mario Gomez ushered towards the bench. The Croatian cost £11.4 million.
Marco Reus' debut season at Borussia Dortmund was almost as impressive. Without winning the silverware of Mandzukic, Reus still managed to bag 19 goals and 16 assists for Jurgen Klopp's team after making the move from Borussia Monchengladbach.