Soccer has changed greatly over time.
During much of the 20th century, teams were expected to raise their own players from their academies or make reasonable transfer deals for players.
Before the 1990's, the most expensive player was Ruud Gullit, who made a £6 million (€7.6 million) move from PSV Eindhoven to AC Milan.
In 2012, the world's most expensive player is Cristiano Ronaldo, who cost £80 million (€102 million).
You can look at teams like Barcelona and Manchester United, clubs that aren't really known for wasting money, but even they spend great sums on wages and on certain purchases.
While it is easy to criticize the biggest spenders for wasting money, these teams have also made some very smart transfers.
In my opinion, the world's biggest spenders of the past ten years have been Real Madrid, Chelsea, Manchester City, and Paris Saint-Germain. All these sides have dished out ridiculous amounts of money on players and have wasted millions of dollars.
However, they have still been on the good end of some bargains. Here's a list of the world's four biggest spenders and their one best transfer deal.
Note: I only picked players who were bought by the club after their expensive takeover.