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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We're less than a fortnight into the summer transfer window, but Europe's top clubs are already flexing their financial muscle.