#4 Kalidou Koulibaly - Napoli (€60million)
Napoli has always delivered in terms of developing some of the world-class football players we have ever seen.
The likes of Lorenzo Insigne, Dries Mertens and Jorginho are at its place, but once such superstar has had the attention.
Koulibaly's tall stature makes it extremely difficult for the attackers to get past him at most of the times.
His leadership qualities and strength is something that has been very useful for his current team.
The Senegalese is rated as one of the most expensive African players along with his national teammate Sadio Mane.
Such is the resilience of the 27-year-old, that Maurizio Sarri is now looking forward to signing him for Chelsea, as Koulibaly has played under Sarri in the past.
His pace, physical presence, and leadership qualities can surely land him to a bigger club with better opportunities, as he surely has the attention.