Fikayo Tomori (AC Milan): £25m
Marc Guehi (Crystal Palace): £20m
Olivier Giroud (AC Milan): £0.9m.
That's not considering add-ons and sell-on clauses included in these deals.
Considering Tomori and Guehi are Academy players and did not cost the club anything to sign, one can only admire Chelsea's ability to sell players for profit.