Romelu Lukaku has joined Manchester United for £75m, Arsenal have snapped up France forward Alexandre Lacazette for a club-record £46.5m, while Everton have already topped the £100m mark for money spent.
But how much are those stars on the move really worth? And what fees will others linked with big-money transfers command?
The CIES Football Observatory has calculated the value of the world's top players using variables such as performance, international status, contract, age and position.
Test your transfer acumen with our quiz and find out who is worth what this transfer window according to CIES.
No cheating - you can check out the entire CIES Football Observatory list here.
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The Whites will move above Sheffield Wednesday into the top six if they beat Blackburn at Craven Cottage on Tuesday.
Button, 28, who joined Fulham last summer from Brentford, told BBC London: "There's 10 games to go, nearly a quarter of a season.
"A lot of things can change so as confident as we are, we've got to make sure we maintain that."
Fulham are the Championship's in-form side, taking 17 points from their last seven games, including a 3-1 victory at leaders Newcastle on Saturday.
Reaching the play-offs would mark a dramatic turnaround in 15 months under head coach Slavisa Jokanovic after they finished 20th last season.
The former Watford manager transformed the squad ahead of his first full season, including bringing in Button - and the goalkeeper praised Jokanovic for his impact.
"The gaffer and his team know exactly what they want from us and drilled it into us from day one," he added.
"Why it's clicked recently I'm not too sure. Obviously there were a lot of changes in the summer, a lot of new faces.
"We're getting to know each other and we've shown on the pitch that it has come together."
We're less than a fortnight into the summer transfer window, but Europe's top clubs are already flexing their financial muscle.
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Goalkeeper David Button says Fulham can not afford to be complacent as they target a Championship play-off place.