4) William Carvalho – Sporting Lisbon to Manchester United
While the Portuguese midfielder is undeniably talented, and enjoyed a promising season with Sporting last time out, his £37m asking price is ridiculously inflated. This is a player with six caps, who’s only made 30 Portuguese top flight appearances in his entire career to date. Even if William Carvalho does maximise his ability, a player who’s essentially a combative midfield work-horse should never be worth such a sum.